C Drive suddently is full - unable to connect to Internet

I run Windows 7.

I have a C drive that is a SSD with 223 GB. Now only 4GB is available.

Somehow, my C Drive filled up and now i cannot open a browser and connect to the Internet.

Is this a virus? Or is it winsxs problem?

Please advise.

---------------------------------------
Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Professional, Service Pack 1, 64 bit
Processor: Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz, Intel64 Family 6 Model 60 Stepping 3
Processor Count: 8
RAM: 8127 Mb
Graphics Card: AMD Radeon HD 7570, 1024 Mb
Hard Drives: C: Total - 228833 MB, Free - 4531 MB; E: Total - 953866 MB, Free - 279754 MB; F: Total - 953866 MB, Free - 865333 MB; K: Total - 1907718 MB, Free - 292608 MB; L: Total - 3815437 MB, Free - 2299540 MB; M: Total - 3815316 MB, Free - 3815110 MB; N: Total - 3815437 MB, Free - 739041 MB; O: Total - 953634 MB, Free - 589169 MB;
Motherboard: Dell Inc., 0KWVT8
Antivirus: Bitdefender Antivirus, Updated and Enabled