I have seen problems with panning when True Type Fonts are used but this is more of an inconvenience than a problem because the symptoms are jerky panning, your problem does sound a little different because it didn't cause the system to completely freeze. In order to help pinpoint the problem its worth trying to answer the following:
Is this a new installation? Has it worked ok before?
Have you updated to a new version of VeSys?
Is the problem on all drawings or just a select few? This will determine if it is drawing related.
Have you tried re-installing VeSys? You didn't mention the version of VeSys you are running, depending on the version you have you might want to check your Installatopn Guide because I just checked my 2007.2 version and AutoCAD LT2000 isn't supported.