Mac Pro freezes up; temporarily fixed by reboot

Question

I have a Mac Pro 2x3 GHz Quad core with 8 GB RAM. I'm experiencing bizarre freeze ups and other malfunctions that are temporarily fixed by rebooting.
The computer is used for live broadcasting twice a week.  Between broadcasting events it sits mostly idle handling email and running a network camera via Evocam.  After I finish a broadcast on Wednesday I copy some audio and video files from the broadcast onto a portable drive.  I leave the computer on. The computer seems to be operating properly when I finish and leave.  Then when I return on Sunday to set up for a new broadcast most often (but not always) I find that the computer begins to act very erratically.  For example, opening a folder on the desktop takes 10 to 20 seconds before it appears on the desktop.  Some files that should be in the folder don't show up.  Then the desktop freezes altogether for up to 1 minute.  The mouse moves across the screen but clicks are ineffectual. I am forced to shutdown and restart.  The computer comes back up functioning perfectly fine.  The cycle then repeats when I return on Wednesday.
I've run TechTool Pro and no problems are found.  The main hard drive checks out fine.  I've noticed a large number of strange (at least to me) messages in console. One of the recurring ones is: 
User Event Agent:***mach_port_mod_refs returned error 15
I also get a lot of console entries beginning with "racoon:IKE packet" or "racoon: IPSec" 
Also entries such as "kernel: /!\ WARNING: 284 recoverable class Fbd error(s)"
I have no idea where to proceed with troubleshooting.  Is this likely a hard drive problem, a computer hardware problem or something else?  All help will be greatly appreciated.
John

Answer 1

I have a Mac Pro 2x3 GHz Quad core with 8 GB RAM. I'm experiencing bizarre freeze ups and other malfunctions that are temporarily fixed by rebooting.
The computer is used for live broadcasting twice a week.  Between broadcasting events it sits mostly idle handling email and running a network camera via Evocam.  After I finish a broadcast on Wednesday I copy some audio and video files from the broadcast onto a portable drive.  I leave the computer on. The computer seems to be operating properly when I finish and leave.  Then when I return on Sunday to set up for a new broadcast most often (but not always) I find that the computer begins to act very erratically.  For example, opening a folder on the desktop takes 10 to 20 seconds before it appears on the desktop.  Some files that should be in the folder don't show up.  Then the desktop freezes altogether for up to 1 minute.  The mouse moves across the screen but clicks are ineffectual. I am forced to shutdown and restart.  The computer comes back up functioning perfectly fine.  The cycle then repeats when I return on Wednesday.
I've run TechTool Pro and no problems are found.  The main hard drive checks out fine.  I've noticed a large number of strange (at least to me) messages in console. One of the recurring ones is: 
User Event Agent:***mach_port_mod_refs returned error 15
I also get a lot of console entries beginning with "racoon:IKE packet" or "racoon: IPSec" 
Also entries such as "kernel: /!\ WARNING: 284 recoverable class Fbd error(s)"
I have no idea where to proceed with troubleshooting.  Is this likely a hard drive problem, a computer hardware problem or something else?  All help will be greatly appreciated.
John