2.53 Partial freezing in sculpt mode

I’m seeing repeated view freezing while in sculpt mode. This is with a Wacom Intuos4, Windows 7 64 and 64 bit Blender 2.53

Typically I’ll have been sculpting for several minutes, then try to rotate the view with SHIFT ALT drag and it stops responding or still thinks I’m using the last brush, apparently ignoring the SHIFT ALT keys. Everything else on the machine responds fine, the process list shows the Blender process only taking a few % of CPU, there’s plenty of memory free.

I can move the mouse around, even go to the file menu and save the blend file, but the view won’t rotate and often the tool circle is stuck at one place on the view. After a couple of minutes it recovers and keeps running.