Cannot Access Specified Resource and other errors

This is a repost from the Malware forums after determining it is not malware related.
http://forums.majorgeeks.com/showthread.php?t=107639

I've been having some trouble with my PC as of late. Typically after a period of inactivity I am unable to launch any applications or open any files. This includes using an already open application to access a file. The three errors that I get from Windows XP SP2 that concern me are:

Windows cannot access the specified device, path or file. You may not have the appropriate permissions to access the item.

You do not have permission to shutdown this computer.

Application failed to initialize properly. 0x0000142...

In trying to correct the problem I would reboot the system or have to power down the computer without a shutdown. I have noticed that repeated restart attempts are required prior to being able to actually load the full OS. What I mean by that is sometimes it will stall at the "Loading Personal Settings" prompt, while others will simply show the desktop without any of its contents. (such as "My Computer" icons, etc...)

One thing I have seen reoccur has been a prompt when shutting down the system that there is a problem ending the task XPCOM:EventReceiver. I'm not sure if this would indicate any other sort of problem.

Originally this came to light when I was trying to update my ZoneLabs ZoneAlarmPro. I was unable to get the update to complete but have since succeeded in updating that application. I have not been able to find any recourse to prevent this from recurring and was hoping to enlist your help.

Thanks in advance.