Prompted to install Yahoo Messenger upon restart even though already installed

Question

I have Yahoo Messenger (3.0.1 beta) installed on my MacBook Air (Lion OS X 10.7.2). It is working fine, however every time I restart my computer and access the Flash Drive (Go - Computer) or the Applications Folder (Go - Applications) I'm prompted to install Yahoo again. I get a Yahoo Messenger installation dialog box asking me to install it. The only way to get rid of this dialog box is to accept the Yahoo agreement and go to the next step for installation - dragging the Yahoo icon into the applications folder. At this stage I can either drag the icon and replace the current one, or just close the drag dialog window. Either way my Yahoo Messenger works fine. If I click the "decline" button the installation dialog box just reappears until I click the "accept" button.
I like to have Yahoo Messenger installed because it allows me to chat with 2 different Yahoo ID's simultaneously - one in iChat and one in Yahoo Messenger.
I contacted Yahoo, but was give this info:
"As of November 15, 2011 Yahoo! Customer Care will no longer provide agent support for Yahoo! Messenger for Mac. If you continue to use this product and have questions or concerns about it, please use the self-service help pages".
This is a brand new computer (and my very first Mac) and Yahoo Messenger was the very first program I installed. Despite the annoyance upon restart I can use both programs (iChat and Yahoo Messenger) together without problems.
I have tried removing all traces of the Yahoo Messenger program using "Appcleaner" and downloaded it again and reinstalled it from scratch, but to no avail.
I would really appreciate some help with this problem.
Thanks in advance.

Answer 1

Hi,
Ok so the Internal "Drive" on your Mac is a Solid State one ?
You say you put an Shortcut/Alias of it on the Desktop.
Was this by going to the Finder's Own Menu > Preferences > General section and ticking the Box to Show Hard Drives/Disks ?
If I "Open" (double Click) an .dmg to Install something I get an icon on the Desktop that looks like  Drive icon (Similar to the USB stick ones) AND I get the item listed as  a "Device"  (in this case GoogleEarth)
I tend to Drag these to the trash when Finished with them as it "Unmounts"/"ejects" the item.  (I used the quotes to show it is a similar action to removing a USB Drive - obviously a CD or DVD would also pop out of the Optical Drive)
Based on the way you describe using the Finder > Go Menu > Computer It get this view
As I Unmount mine I can't really say what happens if I shut the computer down.
As technically it is a Window (the OS sees icons on the Desktop as windows) then I can imagine Lion is Opening it up again if it was there at Shutdown.  (See Message at Shutdown about restating open Windows on next boot and also the System Preferences > General Section).
I will try shutting down and will post after I have done that
8:04 PM      Wednesday; December 7, 2011
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
  iMac 2.5Ghz 5i 2011 (Lion 10.7.2)
 G4/1GhzDual MDD (Leopard 10.5.8)
 MacBookPro 2Gb (Snow Leopard 10.6.8)
 Mac OS X (10.6.8),
"Limit the Logs to the Bits above Binary Images."  No, Seriously