windows xp keeps filling up my c drive

for some reason windows xp keeps creating 1.5GB files in the windows folder
and filling up my hard drive. i had my hard drive in 2 partitions, 1 for
windows xp and 1 for my downloads. my c drive was 10GB and my downloads
drive was 20GB. windows created 5 files called 1, 3, 5, s and y. and
filled up the drive. i used partition magic to resize the partitions to
have c approz. 16GB and my downloads to 14GB. after i restarted 4 more
1.5GB files were created called 2, 4, 6, and z. i have no viruses or
spyware, i already checked. i only have memturbo 2, system mechanic 4,
ad-aware 6, aol 9.0, kazaa lite, grabit (newsgroup downloader), pc-cillin,
voptxp and power dvd 3 on my computer. this never happened before. does
anyone know what is causing this?