I've just installed Photoshop CS4, both 32 and 64 bit versions, on a PC running Windows 7 64bit.
My problem is with the x64 version which doesn't show guides when any tool ( eg crop, pen, ruler, lasso etc etc) is used until the mouse key is released. For example, using the lasso tool the path being traced doesn't show until the left mouse key is released.
The x86 version works properly and I've made sure all preferences are the same in both versions.
Am I missing something blindingly obvious (probably!!) or have others had the same problem?
After lots of Googling I've discovered quite a few people reporting problems with the latest NVIDIA 64 bit driver, although not specifically related to Photoshop.
So that's probably the culprit.