This may be of use to someone - I had this problem with trace.log, and couldn't get Bootvis.exe to solve the problem.
Here is what I did to solve it: - it's worked for me so far:
During boot, press F8 twice to get startup options.
Select safe mode, with command prompt
log -on as administrator
At the prompt, navigate to Windows\system32\logfiles\wmi\trace.log
(you still can't delete the file at this stage.)
use the command "attrib +r trace.log" without the quotes
(this stops windows altering this file anymore, by adding read only)
Restart windows normally
Go to the file in file-manager/explorer
Delete file
Create a new trace.log file (using notepad, and save it in the same directory where you deleted the original)
right click the file, and change attributes to read only
You should now have a file, sized 0 Kb, which can't be changed!
I hope this is helps.
Mark - former DOS user - bring back DOS!