Thursday, March 01, 2007

cannot open the file: mk:@MSITStore: ...

Rick Strahl saves the day again in this post where he explains the "protection" mechanism for files downloaded off the internet in Windows and the "Unblock" option in the CHM file's Properties. If that doesn't solve it, read on.

Sometimes, while trying to read a Html Help chm file (STOP MAKING CHM FILES!), you get an error like "cannot open the file: mk:@MSITStore:idiot.chm". Googling it you quickly find out that the issue is the HHctrl.ocx file in Windows\System32 and that there are more than one version, the newer ones not always being better than the older ones.

There are a lot of suggested solutions on the web, from manually re-registering the OCX with regsvr32 to downloading the "right version". If you want to try those, you want to check the HTML Help - Diagnostics page, look for MJ's Diagnostics, a piece of software that tries to automatically find the Html Help problems and fix them. Well, that didn't work for me, though.

The solution I found: HTML Help Switcher 1.3, a utility that changes the Html Help OCX to any version you want with a click of a button.