I am not having this problem. Are you rooted? If so what rom are you running. This could be a rom issue. If you are not rooted you could try to reset your Market. To do that you need to go to settings > applications > manage applications > go to the market, hit clear data, it will tell you that you are about to delete your information, say yes then back out of your settings and go back into your market. You may have to agree to the Market's Terms and Conditions again but that should get you running.
The Market on my daughter's Incredible was doing that the other day and I reset the Market and now she is not having any issues.