hi, thanks for the interest. VW just freezes, mouse still works, no error messages and have to force quit but every now and then have to restart the whole computer. have no other apps running in the background except the launcher. there is no specific operation that seems to cause the problem and no specific drawing file just happens with alarming frequency. have rebuilt desktop, reinstalled OS, reinstalled VW even from other disks using different dongles. can't see that it's hardware as computer is 2 months old and every other app i use runs fine - photoshop, quark, office, cinema 4d. VW 8.5.2 works on the same computer without any problems. sorry i can't be more specific but any ideas you have would be appreciated,