Opening files quits / crashes programs

[owen_e]

hey folks.
my first post. so ill stick to the rules;

XP Version: Unsure. (Got when bought computer)
Antivirus: Norton AV 2003

Im havin a real pain in the ass problem when trying to open files in programs like Dreamweaver MX04, Illustrator 10, Photoshop 7. Sometimes when I am browsing for files within a program and try to 'open' / 'insert' / 'place' them into the document, the program just quits. (Closes down with no warning).
It usually happens when I first open certain folders. The same thing sometimes happens when I browse through Windows Explorer, but not all the time.
*Not when I 'double-click' to open a document*

I cannot find any obvious link between the folders I open when this happens, the programs that are open and the types of file. They are mostly .PSD, .AI, .GIF, and .JPEG in the folders. But sometimes also .DOC files

PS. Could this have anything to do with transporting the folders with a USB Flash Drive? This is a possible link between the folders.

PPS. I have uninstalled the Illustrator CS trial but to open .AI files I have to 'Right Click' > 'Open With...'. Windows doesnt seem to remember this. What can i do to fix this?

Any help would be greatly appreciated.