1) you may be kept from getting files if you aren't sharing enough files.
Are you sharing enough to not fall into the "freeloader" category? see preferences for uploading if unfamiliar...

or

2) as the previous user pointed out, the server could be busy / at max distributing

and

3) to agree with another...This is a wonderful OS. It is huge and important to everything else on the computer working well. yes, I was at first irked at the ful-priced upgrade, but it is excellent... shop around, get the support, the extra programs, and give the support to Apple to further encourage development...

If it is too expensive look at Yellow Dog Linux, or some such variant.

Cheers