I am currently trying to format a (supposed to be 500 GB HP flash drive from exfat to NTFS. I have it formatting, or at least "saying it is formatting" by using the "Disk Management" component of windows 7. I had to do full format "not quick". Quick failed, just like the other suggestions here did for me. I has taken almost 2 days, ok, maybe not 2 days, but up to about 30 hours, but is now at 94 % complete. Disk management is horribly slow, but seems to be working. "or says it is". Will post if it worked afterwards.
UPDATE
500 gb flash drive completed NTFS healthy drive. Transferring a 19.2 GB file currently as a test. It is slow, but was expected. As long as it actually transfers it all. I can live with that. :)