Welcome to Justanswer.com, my name is ***** ***** I will do my best to assist you.
This issue can have one of three causes, it could be a bad windows update or other update, it could be an isue with your video card / driver. Or an issue with the dock itself.
if youd prefer, I can quickly connect to your computer from here and resolve the issue on screen in front of you.
Or, I can try and guide you via written support through the needed repairs, how would you prefer to proceed?
Not a problem.. First things first.
What version of windows do you have installed on y our machine?
Windows 7, or windows 8 or 10 ?
For now, we will proceed with written support. It will save you a bit of $$ and we can always go into remote support if needed.
Since you say the problem only began recently, lets try to turn back the clock with a system restore.
This is a great step because it wont erase y our files, emails or documents, and if we dont like the outcome we can undo it.
That link will show you how to complete the system restore.. Just make sure you choose a restore point that was at least one day before the issue started.
Once complete, send me a reply and let me know if the machine runs normally with two monitors.. Or if the issue persists.
If the issue persists, we will continue repairs as needed. Also, I realize that it may take some time before the issue starts again, so please dont feel like you have to get back to me right away. ( unless something goes wrong with the system restore or unless you immediately realize it didnt fix the issue )
when you say thats the only restore point.. Did you click the box where it says " show more " or Show all / older restore points" ?
If the issue started before that, the system restore probably wont help. Though Its still worth a shot, since we can undo it if needed.