This isn't a site issue, nor do I think eBay is telling you that the items you're selling are fake. You may have run up against a "category limit" if you're selling a high-profile brand.
I don't know exactly how those limits are established, but I suspect eBay has some sort of agreement with brand name owners that only a certain number of geniune items will be able to be listed on eBay by non-authorized dealers. This happens with high-profile and very desirable brand-name items in a number of categories, and not necessarily only with new sellers (I had it happen to me once or twice last year in selling authentic vintage Chanel items).
You can wait until the next month to relist, when you'll find your limits will have re-set, or if you meet the minimum seller standards and have no active cases against you, you might be able to have your limits increased -- see if there is a link in the message you got from eBay.
The information in the following link might help (click on "Categories" in the text to see the list of categories with limits - clothing is one of the bigger ones).
http://pages.ebay.ca/help/sell/sellinglimits.html
