im not in any way shape or form an expert, but that sounds like you having data drop trouble and not problem with the market itself, just to try and get ya some more assistance, give out a lil more info maybe someone very much more knowledgeable then me will jump in lol
what rom do you have? if any (also if your are running a rom did u flash the gapps if it was needed?)
do you get errors or trouble loading internet pages at any point, or is it strictly with the market?
try loading up a bunch of different internet pages and see if you get connection error or connection unavailable or anything like that