At least on Win7, Intel gives you a control panel applet showing video memory information. Is that in XP?
I know of one other place it's listed: Aida64.
It's funny you mention this, since under the Windows 8 Consumer Preview I know of a third-party app that randomly does something very much like what you're describing. When it happens, I'm able to open Task Manager, and perhaps Alt-TAB between a few windows, but I can't actually DO much, like shutting down. Ending a task in Task Manager doesn't even work. It's as if the windows aren't updating properly, and I eventually have to cold boot. It's not an Intel-specific problem though, since I know someone who's seen it with AMD. But it sounds awfully similar to what you're talking about.
Yes the XP version does have the option in the Applet to show how much memory is being consumed.
Up until the point of finding the applet option that shows GPU memory consumption, I had been profiling my application like crazy, even had someone from the Microsoft WPF/XAML team profile the application and they also couldn't find any memory leaks in the application.
Once I discovered the problem was only surfacing when the GPU memory was nearly maxed out, that was the day I discovered it wasn't actually a problem in my application, but it was in-fact a problem within the driver. I have noticed if I enable BitmapCaching on more elements, the GPU memory consumption increases exponentionally.
For the first few hours I can see the GPU memory stay flat as it should, but then after about 19 hours, it starts creeping up and never stops.
Well it certainly appears I am not alone in this.
WPF GUI freeze in hardware rendering condition - http://communities.intel.com/message/126791#126791
Problem with WPF and Intel HD 3000 Graphics - http://communities.intel.com/message/151240#151240
There is obviously a problem with these embedded graphics cards and/or drivers.
What I find most scary is the fact that in the other cases reported on these forums, Intel is ignoring the problem (walking away or not responding at all).
The amount of time and effort we have invested in Intel Embedded Technology and it's failing us.