Deleting files from the system partition in Win 7?

[IronWing]

I have a 100MB system partition which has only 7megs free. I can't see any files or directories in the partition even with Windows Explorer set to view hidden and system files. MS Security Essentials says that there are 39 items in the partition. Backup fails to run because there isn't sufficient free space in the system partition. Win 7 won't let me format the system partition. Any ideas on how to clean out the system partition so I can run backups?


Edit: I figured out that I had forgotten to enable showing hidden system files. I can now see some of the files in the partition. The folders are:
$RECYCLE.BIN
Boot
System Volume Information

Plus one file:
bootmgr

The total size of these folders and files is ~14MB yet for the partition there is 93.3 MB used. Disk cleanup didn't do anything.

 

[IronWing]

I found out what was clogging up the partition. I recently moved the OS to a new ssd. Samsung's migration software leaves behind a hidden NTFS log file on the system partition that is invisible to Windows Explorer but can be viewed with the chkdsk command. The file is normally about 2MB but the migration software left 54MB in the file. I was able to use the chkdsk command to shrink the log file back down to size. I'm running the backup again. So far, so good.

Edit: Back up completed; all seems to be well now.