Which version of Photoshop???
I have had absolutely no problems with either PS CS2 or PS CS3.
Did you install the public beta of PS CS3 which Adobe released. If you did,
there is a script which Adobe released, which you were supposed to run before
installing the retail version of CS3. People who neglected to run this did
run into problems on any of MS's operating systems (both 32-bit and 64-bit).
If this is true for you, uninstall Photoshop CS3 and then run the scripts
which can be downloaded from
http://www.adobe.com/support/contact/cs3clean.html