Appearance of icon on desktop when saving a file

Whenever I Save a file on the Desktop, first a white blank file icon appears and then a regular file icon replaces the blank one. I guess this is the usual process that takes place and normally is not noticeable. But for some reason, the process is taking longer and is noticeable.

It usually happens when I Save files with Excel and Word. It doesn't seem to happen with PowerPoint or TextEdit. Anyone know why this is happening? Anyone have a solution?

I should mention that I've recently upgraded my RAM to 640 MB and my operating system to Tiger, so I don't know if this has anything to do with it. Also, here's what I've tried so far...

1) Downloaded and re-installed OS X 10.4.8 Combo Updater from Apple's
website.

2) Ran 'Repair Disk Permissions'.

3) Ran 'Repair Disk' from the Install disc. Apparently no repairs were
necessary.

4) Ran 'Apple Hardware Test'. All components passed.

Thanks!