There are lots of fake files around now. If you're looking for new releases/really popular files, you're likely to see a high percentage of fakes. These often have lots of sources (up to 100 per file) & will sit connecting for ages before going to 'need more sources'.
Stay away from files with huge numbers of sources... try going for files with 10 sources or less. Also vary your search terms a bit & try the All Types search. If some things are downloading, I'd say you're just seeing more fake files (as we all are).

As for your really slow downloads, are all your downloads slower than usual?
As a test, download a file from here & see what speeds you get
http://www.magnetmix.com/video.shtml

Do a speed test & tell us the result
http://www.dslreports.com/speedtest?more=1

Who is your ISP? Have you tried using other p2p apps & if so, does the same thing happen?