CCleaner PRO v5.33.6162 crashes during drive wipe

Drive wipe, C disk, 1 pass, crashes after about processing 4% of free space only. A crash report is sometimes generated.

Ran ccleaner in debug but there is no dump or crash report generated.

I have performed system restarts, uninstall and reinstalled ccleaner and crash still happens.

Have run drive wipe on C drive on this system for last 2 yrs without a problem.

System is windows 7 ultimate, sp1, 32bit.

Does it say anything in the Windows Event Viewer about it either under Application or System around the same time?

what about from Safe Mode?