I had the same problem recently, and I can tell you for a fact it was not disk space related (for me anyway) I have a 500Gb hardrive, partitioned into 5 sections (4x100GB 1x 84.6Gb) I use one of the 100Gb partitions for downloading music to and its still 90% empty. All I did to solve the problem was run a scan disk on the drive, then defragment the entire drive (all 5 partitions). This solved my problem, maybe this will help you.