Gray-screen freeze when connection Thunderbolt display

Question

When I connect my 27" Thunderbolt Display to my 15" Macbook Pro it freezes up and I get a gray screen.
But when I start-up without met TB Display I starts fine. What could be the problem?

Answer 1

Welcome to AD!
Try using Disk Utility to do a Disk Repair, as shown in this link, while booted up on your install disk.
You could have some directory corruption. Let us know what errors Disk Utility reports and if DU was able to repair them. Disk Utility's Disk Repair is not perfect and may not find or repair all directory issues. A stronger utility may be required to finish the job.
After that Repair Permissions.
No need to report Permissions errors....we all get them.
Also here's a Gray Screen Apple doc.
DALE
p.s. It would help us, so we can advise you correctly, if you would fill in your Mac's specs. in My Settings over on the right, near your name and under the logout choice, please. Over there-->>>>>>>>
If you're unsure about the specific Mac model you have, you can plug in its serial number here and it will give you the model and its specifications.
DALE