One of my users is suddenly stuck at 640x480 resolution when connecting to the host computer. This host machine happens to be one of the few with only a single monitor. I have updated drives, rolled back drivers and she has changed all the settings to no avail. It's completely unusable this way. Is there anything else that we can try?
What operating system version is the Host PC currently running?
Can you confirm the GoToMyPC software version installed there?
@MarykayH It sounds like you've done all the pre-required troubleshooting for a problem of this type. If it persists when connecting from different clients then I would suggest creating a case through Customer Support.