I've been using Limewire for years now and it has always worked perfectly for me. As of lately though, I download about 40 songs and 3 of them will not download at all. I've tried downloading these songs from different hosts but they always "Queued" and never actually start downloading.

QUEUED = your LW is too busy to handle them. Are you sure it says queued or just connecting for ages, or waiting in line. If it says waiting in line, then the user who is hosting them probably only has one upload slot available & is difficult to connect to. If it says connecting for ages & then eventually says need more sources, then it may be a fake file; Recognising fake files

If waiting in line, try browsing host, also keep searching at different times of day. Some gnutella programs are difficult to connect to. Shareaza & Gnucleus are often such.

I keep getting that when I try to download a very popular movie. Although there appear to be nearly a thousand hosts apparently sharing the file. Every time I double click on the file, I keep getting "Awaiting Sources".

I mean, I'm sharing some very sought after files and a quick look at my monitor shows that people are clearly able to access them cos they're uploading like mad. Have I been blacklisted or something ?

A movie with almost 1000 hosts is very likely a fake, especially if it's a new release or really popular title

Search again, vary your search terms, try the All Types search. Stay away from files with lots of sources, go for a file with 10 sources or less, or those with a modem source.

For movies, always check a file before download with Bitzi. A file with heaps of sources but no Bitzi rating is often a fake.
How to use Bitzi

For music, try the tips in this thread
How to find music

And for some general info about these fakes
Info about fake files

Well it would appear that EVERY file on the search is a fake because Bitzi says it has no information about the bitprint.

If it's a new release in cinemas but not out on DVD yet, there's every chance that all the files are fake. You might see a couple of crappy camcorder versions but really, until a movie's out on DVD you're unlikely to find good sources.

If it has been released on DVD, try searching at different times of day when people in other time zones are online.