Apps minimizing unexpectedly ?

Hi,
I have a problem on my pc which runs xp home. When I'm running apps with no notice the app suddenly is minimized, and the desktop is shown. If I click on the app icon in the taskbar the app returns to orginal window size. Sometimes it carries on working fine after this for a while, sometimes it has frozen. I notice the problem more often with games and I don't see the problem with say with messenger/firefox. After these incidents explorer still seems ok, and I can open new programs, browse files etc.
I have swapped to another type/make graphics card with no change.
I've run memtest86, tested with ad-aware, S&D, and AVG anti virus and have not found any problems.
I'm not sure where to go from here ? Any suggestions ?
Tony

Is this a new problem? Were things working OK previously? Any new hardware and or software?

Also view your Error Log via:

[1] Start Menu
[2] Help and Support
[3] Pick a Task
[4] Tools
[5] Advanced System Information
[6] View the Error Log

Look for any synchronous entries.

Also: look in your Event viewer: rt. click My Computer then click Manage then Event Viewer.
Or: Administrative Tools/Event Viewer or Start/Run/ eventvwr
Open the system as well as the application tabs & look for X errors. Click error line for details.
Post back the source & event id & Description especially of errors that seem to coincide with this issue.
Also check the Information lines that might coincide with this issue.

How to view and manage event logs in Event Viewer in Windows XP

Hi,
This is a new problem, everything used to be fine. If I had to pinpoint something that seems to have happened at about the same time, it was installing elder scrolls4 : oblivion, but I'm not sure about that.
I'll have a look at the other items you suggested later and see if anything shows up.
Tony

You might want to try a System Restore to a point prior to that last install.

start > All Programs > Accessories > System Tools > System Restore