I'd still go with seeing if you get this issue on more than one install of Dynamics GP as well as more than one machine.
Remove any third-party products, Citrix, customizations to verify whether any of those are causing the issues to occur.
If the issue is completely random in occurrence, you could be potentially running into a connectivity/network issue with Dynamics GP and SQL Server. As a test, if you install Dynamics GP directly on the SQL server, do you get the same issue?
If the users all use only one instance of Dynamics GP, you can try re-naming the GP directory when all users are logged out, then run a Repair against it via Control Panel > Programs > Programs and Features, which will completely re-create the entire GP directory, minus third-parties, customizations.
You can then have users login to this 'new' GP instance and see if this issue still occurs. If not, add back any third-parties, customizations and such one by one, testing after each one, until the issue returns.
--if it returns, you most likely have the cause.
--if it doesn't return, then it could've been an issue with the GP directory/files themselves.
Thanks
