Photoshop :: Warning Panels Not Displaying Unless Another Program Refreshes Screen

Photoshop CS4 v11.0.2  winXP pro sp3

If one uses e.g. canvas size and chooses a smaller canvas, normally a panel appears 'the new canvas size is smaller, some clipping will occur, proceed or cancel. Likewise if you print something and its wider than the pagesize, you see a message panel appear, the image is larger..some clipping will occur, proceed/cancel.
 
These panels have ceased showing, but unless one clicks proceed or cancel on them, photoshop cannot progress,...not responding results. Trouble is you dont know if they have shown up but are hiding. Tried moving the image but it leaves a white space behind and the panel is not behind anyway, or under the main photoshop window.
 
If you launch e.g. word and print something, then minimise, often the panel then shows itself, from then on its ok ! Until one closes Photoshop then its back to its freezing ways next time after launch until refreshed with Msoft word printing, though that doesnt always resolve it.
 
It also freezes up when closing images using the X top right of image.  I had thought I had spoted a trend to fall over on jpg images but not so I think now.
 
Tried for a full reinstall, no joy. updated video driver ATI radeon HD3450, the ATI driver wouldnt go on, couldnt find a suitable driver it said !... but the one from the Dell website did, turns out to be the same ! 1/12/2008  8.561.0.0  though ATI have a more recent one Feb 2010.
 
We also run Sophos antivirus.