Go to Start - Programs - Acessories - System Tools - Disk Cleanup and run the program.
This should remove all temp files from your system (caution - could take a long time). It's totally safe, you don't need any of them.
The error listed seems to be related to something in a temporary folder, so deleting them all might clear it.
Do you have an anti-virus program, and is it up to date, and have you done a recent full scan?