C: Drive full!

[FlyNAVY]

Computer in question here is a Toshiba laptop running Win7 64 bit. It has a single 500GB hard drive which I have split into two partitions: C: for the OS and all programs, and D: for data files, such as pics, docs, etc.
The C: partition is about 160 GB, of which less than 90 GB is used, leaving about 70 GB free. Problem is that occasionally, the C: drive will show redline with only about 10 GB free. I've searched every folder and file in C: drive to find what is taking up to much space, but have found no culprit. Short of performing a recovery from backup (which works), is there another way get this partition back to normal level of about 70 GB free? Performing a recovery will lose recent e-mails, which are stored on C: drive. Thanks!

 

[TrainableMan]

I would try a product like CCleaner and see if it can free up the space when C: shows as full

 

[FlyNAVY]

I would try a product like CCleaner and see if it can free up the space when C: shows as full

Thanks for your reply. I've already tried CCleaner but problem remains.

 

[TrainableMan]

Then it may be hidden system files, for example if you have windows 7 backup enabled and going to C: it will eventually fill the entire drive. On a drive that small you definitely don't want backups on C:

 

[John700]

You can use tools like SpaceSniffer to try and find what file/directory is taking most space