My efforts to remove malware from a network external hard drive connected to my Intel based iMac is now causing programs to hang when I try to open them.

Question

I own an iMac, recently updated with OSX 10.75. It is the core computer on a home network shared with an iPad, Apple TV, two network printers,my wife's laptop, two iPhone, a BlackBerry and a BlackBerry Playbook. I am experiencing three if not four problems that are overwhelming.
My original problem is associated with Windows emails files or documents  stored on my external network  hard drive. One or more has malware and is sending malware laced files across the Internet to points unknown.  As someone pointed out in a forum my iMac may be hosting,sharing and propagating Windows malware.  I originally used Trend Micro software on my IMac to monitor any viral activity. Two weeks ago I noticed a number of notices from servers around the world saying my message was not undelivered. Since I had sent messages to the people I simply deleted the emails. Next I noticed the emails on my BlackBerry and my BlackBerry playbook.I configured the Trend to do a complete scan and although it did a complete scan it did not perform a full network scan. It did identify a series of .x27 document files with the same name tbut each had a sequential number. I assumed hat these were the source files that had  sent out the email documents selling Viagara and othernproducts.  I manually deleted thousands of the source documents and the files. This caused some disruption to my computer but it did not produce a hardware or software problem. By following this effort in conjunction with security scans I do believe the malware was activated by Iranian students who were able to activate the malware through my BlackBerry and BlackBerry Playbook.  I learned this from an encounter I had when trying tondelete these files on my computer and my BlackBerry.
When using my PlayBook after deleting the files from my computer I noticed more messages being returned from servers.  I realized that email accounts connected to my BlackBerry and BB Playbookn were not protected from this problem. As I searched for remedies I learned about turning on the firewall in the previous version of Lion but that did not stop the BlackBerry problem. Each time I deleted a source file on my computer more documents were released. I eventually received McAfee from my ISP. It provided security on the entire network. My first full scan of my external drive identified two malware files. One of them was associated with the Cialis ad the other was from a firm in the Middle East called ADP.  it could not remove the latter file.
Moreover each time I attempted to remove the source file from my hard drive a file labeled A239A076F would show up on my Blackberry.  As I removed them thousands of these files would show up.  Ultimately I eventually disconnected the external hard drive and removed the battery from the phone and not use the email accounts these messages had used to enter my iMac.  I am contacting ATT about BlackBerry data security and switching to a different phone for business purposes. I will probably change to an iPhone or Android phone for business purposes.  I am also looking at ways to resolve the malware on that drive. There are a number of business and personal files on thatbdrive that I hope to keep. I dread having to pay McAfee to configure the software to eradicate the malware.
Moving on...last week I updated my iMac to 10.75. It simultaneously updated every Apple based program as promised. It did not update the non-Apple programs.  I am not an IT professional and assumed that it had done so.  On Saturday I attempted to download a file associated with my router extender using my untethered Playbook and BlackBerry desktop software. The program hung. I attempted a reboot and it reopened with the hung program.  It created an alias file on the desktop.  My inclination led to put the alias file in the trash can and delete it. My computer did not respond well to that action. It has been rebooted with Cmd-s-esc tens of time to see if that would activate a file check. It did not. I was able to run a disk utility check. And in spite of the hung process it eventually said the drive was okay.
Long story in a nutshell. My iMac is responding as if it is looking for a subprogram to complete its a function. Or it is attempting to finish the BlackBerry operation it began on Saturday. I hope this makes sense to someone and the know how I can restore functionality to my iMac.
Thank you.

Answer 1

I think the McAfee suite will do the trick when I pay them a one-time fee of $69 or $179 for a year for unlimited support.
Your call of course but IMO a waste of money. Please read this first:
There are many forms of ‘Malware’ that can affect a computer system, of which ‘a virus’ is but one type, ‘trojans’ another. Using the strict definition of a computer virus, no viruses that can attack OS X have so far been detected 'in the wild', i.e. in anything other than laboratory conditions. The same is not true of other forms of malware, such as Trojans. Whilst it is a fairly safe bet that your Mac has NOT been infected by a virus, it may have another security-related problem, but more likely a technical problem unrelated to any malware threat.
You may find this User Tip on Viruses, Trojan Detection and Removal, as well as general Internet Security and Privacy, useful:
https://discussions.apple.com/docs/DOC-2435
The User Tip (which you are welcome to print out and retain for future reference) seeks to offer guidance on the main security threats and how to avoid them.
More useful information can also be found here:
http://www.reedcorner.net/mmg/