I'm running Studio 10.8 on an Athlon 64 3500 PC with 256MB of video memory and a dual port video adapter (ATI Radeon).  I run Studio across two monitors, with the previee window enloarged and running on the secondary monitor.  The last time I used Studio for anything serious was last November, when it worked flawlessly.  Now I come to use it again and the preview window on the second monitor looks like it has reverted to low definition mode - about 5fps and very grainly.  When Iswithc preview back to the primary monitor (in it's default small window it seems fine.  This problem presents both on old projects (Which were fine at the time) and for newly-captured material.  As I'm not a regular user of the product I may be overlooking something obvious, but I don't know what.  I'm certainly not aware of changing anything in setup to account for this, although I have installed some other software since (namely Cubase 4 Studio - a sound recording suite).  Does anyone have any idea of what might be going on and how I might fix it?  Thanks in anticipation.    Chas.

Do you automatically accept windows updates?

I'd check that you have the latest/correct drivers for your video card, or perhaps something else has altered a video setting such as hardware acceleration  

I've downloaded and installed the latest video drivers for my card (Radeon x700).  Makes no difference.  I also hoped that by uninstalling the card and reinstalling it with the new drivers any inadvertent settings would have reverted to default.  I've also switched on and off hardware acceleration, to no effect.  However, a little further investigation reveals that it is almost certainly a secondary monitor problem, because if I move the studio window over to the secondary monitor (I have it set up as an extended desktop) the low frame rate becomes apparent in the mini preview window.  Asigning the full screen preview to the primary monitor results in a full definition full frame rate preview.  Not sure if any of this helps to point to a reason why it's happening, however.  This is a workaround that I can live with but I'd still like to know what's going on. 

Have you experimented with the resolution of the second monitor?

Hopefully someone with and ATI card running two monitors will pitch up soon...... 

Do you have a spare video card lying around? Is it possible it is hardware issue? Perhaps a power supply or cooling problem? Just an uneducated guess, but I figured that I would share, just in case it made sense.

I had considered a hardware issue - thing is, other video applications play at full frame rate on this monitor with no trouble at all.  It still seems to be something peculiar about Studio and extended desktop arrangements.