Thanks Naomi and Neil,

I'll get them to check the driver situation, Neil.

I've read the thread relating to the grid height. I've experienced that problem myself in the past but that's not what's causing the problem here. The specific line of code that it trips up on is contained in a PRG file and says:

define window w3 from 0,0 to SYSMETRIC(1),SYSMETRIC(2) color rgb(128,128,128,128,128,128)

There is no grid involved in this window.

I will check out whether or not any changes have been made to font sizes or other standard Windows settings. This particular user is operating on 64 bit and using Windows 7 - wondering if that may be a factor?

hanks John