Time lag when using commands for the first time

We have been on Nx9 for a while and at some stage it has devloped a lag of around 30 seconds when using some commands for the first time. This is experienced by all users here and is occuring often and seemingly randomly. For example the first time that I use the Measure Distance command I wait for 30 seconds before the dialog comes up, during this time Nx is frozen, all I see is the wheel spinning (time wasting) icon. The second time the command is used, the dialog appears intantly.

So not sure if this an Nx issue or a system issue like antivirus etc. Does anyone else experience this problem?

Thanks

Keith Irvine

Dell Precision T3610

Xeon E5-1620 v 2 Quad Core 3.7 GHz

24Gb RAM