When I try and access the menu and then "photoshop " (or press the F1 Button) in photoshop cs2 I get the following error.

"the operation could not be completed"

I then press ok on this and the following pops up.

"The instruction at "0x00864a4d" reverenced memory at "0X00F40B08". The memory could not be "written". Click ok to terminate the program"

I have win xp professionals sp2 and am using cs2.
Pc is lintel dual core with 2gb of ram.

I have uninstalled and reinstalled but still recieve error.
Does anybody have any ideas how to fix this?