BleepingComputer.com: Ghost files?

Not sure if this is quite the right place for this and if it is if this isn't a dumb question, so if I'm wring on either forgive me. I've been trying out a variety of P2P programmes including shareaza and gnutella just recently, just to have a look see. After the last attempt with Shareaza (which seems impossibly slow and unreliable downloading videos/DVDs) my laptop staring indicating that the C: drive was nearly full, which wasn't really possible. Having looked through it, I noticed a number of new, strangely-numbered folders (for instance (7419(]P388hU7nTKc) which contained a large number of unknown files, many of which were 216 Mbs. This was what was blocking my drive and after I got rid of them all was back to normal. Was this the Shareaza? I also use Eraser after some bad experiences with trojans/malware/viruses, CCleaner and have a Comodo firewall. I regularly use Malwarebytes as well. Presumably Windows doesn't create these 'ghost files'?

I am not exactly sure why, but just a tip, I would defrag your harddrive now if i was you considering you just removed a bunch of huge size files from your HDD. ;)