I have just switched to Win 7 64 Bit and I cannot open any of my chm files, created for the help text of a desktop application we develop. When I try to access them from the software, nothing seems to happen. When I try to open them from Windows Explorer, I get "Cannot Open the File: Mk:@MSITStore: ..." for the selected .chm path/file. I have tried several things found online, but none have helped yet. The files on my network and local are both effected. AV is Trend Micro CHM file created/compiled using RH8 Any assistance would be greatly appreciated.

Hope this helps Microsoft recently released a security patch that makes it impossible to view CHM files that are stored on a network drive (as opposed to CHM files stored on your own computer). The help file will appear, but instead of the topic text you will see an error message "this page cannot be displayed". The security patch and its effects are fully described on Microsoft's web site at http://support.microsoft.com/kb/896358 If you trust all the computers on your LAN or intranet (and the people using them), you can lower the restrictions on the Local Intranet zone to allow CHM files to be displayed with the following steps: 1. Click Start, click Run, type regedit, and then click OK. 2. Locate and then click the following subkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions If this registry subkey does not exist, create it. 3. Right-click the ItssRestrictions subkey, point to New, and then click DWORD Value. 4. Type MaxAllowedZone, and then press Enter. 5. Right-click the MaxAllowedZone value, and then click Modify. 6. In the Value data box, type 1, and then click OK. 7. Quit Registry Editor. If this solution does not work for you, please see http://support.microsoft.com/kb/896358 for alternatives.

I had the same problem I tried everything specified in the support. My folder name that has these .CHM files has "#" that was the reason for me. Just to update so that this might help someone in future .