What Gets Cleared At Log Off & Re-Boot?

I have Win 7 Pro 64 bit SP1 and use Adobe Photoshop CS5.1, and have done for a long time without problems. All my software is fully updated.
In the last two weeks I've encountered a problem where images won't display in Photoshop if I've closed it and done something else for a couple of hours or so. The images show in the Open Recent list in Photoshop as though they have been opened but do not appear on screen. When this happens I cannot access the Color Settings in Photoshop either.
The only way I have found to resolve it is to log off then log back in. After that everything is OK with Photoshop again.
I have tried everything I can, made sure my graphics card driver is up to date, tried older graphics drivers. Removed then re-installed Photoshop. Then I completely re-installed Windows and started from fresh.
I have posted on the Adobe forums but nothing anyone has suggested has worked, though two other people have reported they have started to get the same issue.
So my question is, can someone tell me what is getting cleared, changed, at log off that they think could be connected to this.
I use CCleaner to clean up my temp files etc on a daily basis; but using it when I encounter this problem doesn't fix it.

Welcome to Windows Seven Forums.

In all honesty, I think your problem lies with Adobe Photoshop, and not Windows.

I'm currently using Adobe Design Premium CS5 and after an intensive period of photo editing the application freezes for a few minutes.

I've tried getting answers from Adobe and all they can suggest is upgrading to version CS5.5, which I refuse to do.

All I can suggest is you try and find an answer through Adobe's forums or raise a case with Adobe directly.

Not What I Am Asking

Maybe I didn't make myself clear enough.

I didn't say I thought this was a Windows issue and I did say I was pursuing it via the Adobe forums, which I still am.

But I am using Photoshop with Windows so I feel this is a valid place for my query which is regarding Windows.

My questions was does anyone know what Photoshop and Windows share that gets reset when you log off?

Because it's only by logging off that this problem goes away.

If so then maybe it will help me understand what is happening and maybe lead to a resolution..

In that case, I'm afraid I don't know.

Corrupted Processes?

Maybe you could take a screenshot of your Process List (in Task Manager, Process Explorer, etc.) after you log in.
Run Photoshop and nothing else.
Take another screenshot after you close Photoshop.
If you compare them, you may find some processes haven't closed properly.

Have you checked your Windows Error logs?

On my PC:
Firefox sometimes doesn't close properly and this causes problems if you try to reopen it.
Rhapsody has a helper service, which doesn't stop when I exit Rhapsody (I haven't noticed any problem caused by it though).