Step 3: Clean Out Your System Junk (Temporary Files and Folders) With Disk Cleanup (cleanmgr) Over time, your computer accumulates junk files from normal web surfing and computer use. If this junk isn't occasionally cleaned out, it can cause JClass Enterprise Suite JProbe Serverside Edition Evaluation CD-ROM to respond slowly or provides an jcdatasource450K.jar error, possibly due to file conflicts or an overloaded hard drive.