I have completed a chkdsk /r (I had done it without and with a /f).
On verifying file data (stage 4 of 5), it says:
the disk does not have enough space to replace bad clusters detected in file 4532 of name \windows\micros~1.net\framew~2\v40~1.303\setupc~1\v45~1.512\netfx_~1.mzz
'the disk does not have enough space to replace bad clusters detected in file 286139 of name \windows\micros~1.net\framew~2\v40~1.303\setupc~1\v45~1.512\netfx_~2.mzz