I forgot to mention that this only happens with a certain somewhat complex dialog window I've written. Whenever these users invoke the script, that's when they see the error.
It's something that doesn't happen all the time (or every single time), but does happen frequently with users who are most active with different images throughout the day (since this script is supposed to get invoked at the very end of a retouch job, and is a checklist of sorts, to make sure the artist didn't forget anything). So the really busy users who work on 4-5 images a day may see this thing once or twice a day. Others who are longer on more detailed files and only output 1 or 2, may be lucky to see it once a day if even once every few days, but it is inevitable that they will see the error eventually.
I'm thinking there's something I've done in my code that causes this to happen. Perhaps an overload resources... and once my script has caused the issue, then my script and only my script (I think) will not run until restart - as other dialogue windows native to PS seem to open perfectly fine (haven't verified if any third party dialogue windows are broken as well, however).