There are a few things that could cause this.  I would recommend (if you can) having another person log onto this person's workstation and then launch Sage Desktop and subsequent application(s).  If that works, then the problem is likely an issue with the original user's profile.  If so, this can likely be fixed by:

1. Log onto the computer as the user having trouble
2. Close all Sage applications
3. Open the Registry Editor, navigating to HKEY_CURRENT_USER\Software\Timberline
4. Right-click the Desktop key and Export it to a location of your choice (this is a backup of that key)
5. Once exported, you can then right-click and Delete the Desktop key
6. Close Registry Editor

Thanks Todd! I am able to replicate the issue by logging into a different Windows account on that machine and by logging into a different Sage account, so the issue appears to be related to the machine and not a specific profile, unfortunately. I was unable to find any Application or Sage entries when we get the error, but below are the details from the System event that gets logged, if that helps:

This error is similarly referred to in Sage's Knowledgebase and would indicate this is a Windows Permissions issue.

Having said that, and now that we've narrowed our scope to the workstation, I would recommend widening the testing.  There are multiple tests that can be run (e.g. Sage System Verifier, or Pervasive System Analyzer, etc.) that may be able to point towards a specific area (e.g. Anti-Virus, firewall, other network communications).  There are enough questions and possible tests to run I would still recommend getting your Business Partner involved.

Getting their "eyes" on the workstation can sometimes identify problems that are difficult to put in writing and watching how it behaves during the test as well as seeing log results or errors are beneficial.  Other questions that may help identify what is going on are:

1. When did this start / when was the last time the user was able to use it without error?
2. What changed between then and the first time they realized they couldn't use it?

That second question usually results in "nothing changed", but obviously something did or we wouldn't be here.  Sometimes what has changed is not something you would have thought would impact your software (e.g. power tools are being used in the office for a remodel, or other new large machinery).

I'm tempted to suggest replacing your Pervasive/Actian client engine (I'm assuming you are still using a client engine on this workstation) with a Server version as this can sometimes resolve permission and other issues.  While it could be as simple as changing the Log On account of the Client Engine service.  But, this could also be leading down a rabbit hole without answers to at least the two above as well as several others.  Swapping of the version of engine/service is a quick test/solution.