Hmmmm, weird.

Have you tried turning Aero off? Although I don't think that's the issue.

Still the same problem :-(
But thanks for the tip!

That's very weird, not something I've seen before (I have a W7 x64 install as well). This happens with both the x86 and x64 Reaper installs? Are there any system variables you can think of that might affect display (multiple monitors, VNC server running, etc)?

Win 7x64 here also, nothing like that. Might have to do with the RC version.

In the past, and not with Reaper, I've had occasional problems with video cards not rendering graphics properly or being too low on RAM if there was a lot of graphics stuff displayed at once. But this was on a G4 and when things were slower.

Hi!
My graphics card is an ATI Radeon HD4890. Yes, I use multiple monitors. I could never live without them. :-)
I use Reaper natively without any virtualisation or something. But i could try to virtualise Win7 RC 64 Bit / Win 7 Enterprise 64 Bit (work laptop) and try it out on the VM.
But sadly, that's no option to make music in a VM...

As an experiment, would you mind running with just one monitor to see if there's any change? I can't think why that would affect anything but it would eliminate a variable.

I will do that on monday, because I am not at home currently.

Unfurtunately, that doesn't help. :-(
I wouldn't say, that this is a hardware problem because every other software runs great. Does anyone uses Win7 64 Bit RC 7100 too?

Yes, I use it :/ this is starting to look like a "cannot reproduce" ticket...

That only appears on my computer? Thats strange... Then it has to be a hardware problem? But, why does every application work, except Reaper?

Do you have any non-standard Reaper display settings (like UI scaling, which is set in preferences/general/advanced)?

No. It's a clean, new installation.

i used to have this problem but never reported it as a bug. i'm using xp, not windows, but it sounds like exactly the same behavior.

in my case, it was because of Task XP Switch

http://www.ntwind.com/software/taskswitchxp.html

every time my mouse would linger on the start menu toolbar (which creates a thumbnail of the app) reaper gui would vanish with the same reappear-when-moused-over

removing this app solved the problem. i post this because of the similarity in behavior.

I don't have TaskSwitchXP installed. :-( But thank you for your notification.

[WRONG]
I.. eehr... I found the reason!!!
It's strange, but... Reaper choosed my default Audio Driver "Toneport UX2 ASIO".. I have some problem with that driver (it's not yet certified for Win7) in other applications... Like, i use a sample buffer of 1024 and still have crackles etc in the sound, althought the application uses 5% of my CPU...
I downloaded ASIO4ALL drivers and the other applications worked fine... With 256 samples buffer and with no crackles (8 Guitar Rig instances at the same time). So does Reaper.
I recognized, that the UI elements are shown again if reaper is not the active window. And I recognized, that the audio driver is closed if Reaper is not the active window.
I switched the reaper driver to ASIO4ALL instead of my ASIO Toneport UX2 and it works now.
What the heck.
[/WRONG]

Okay, stop, it doesn't work. :-( It just looked like it does... The UI elements were visible for about 10 seconds.. But when I created a new track, it started again... Okay, nothing with the driver.. I will search on...

By the way, sorry for my bad english :-)