This is a long story so I will not try to recreate it here.
Summary:
- MSCOMCTL.OCX is a set of 32-bit controls that were provided with the Microsoft Visual Basic 6.0 programming environment
- FLAC frontend is written in Visual Basic 6.0 (it seems, I do not use FLAC)
- To use 32-bit controls like MSCOMCTL.OCX on a 64-bit version of Windows 7 they have to be installed and registered in: C:WindowsSysWOW64 to run in the "WOW [Windows on Windows] emulation environment
- On my install of 64-bit Windows 7 I found MSCOMCTL.OCX already present in the C:WindowsSysWOW64 directory, I am not sure if its there by default or if I installed something that placed it there for me.
- If you go to your C:WindowsSysWOW64 directory and see MSCOMCTL.OCX already in there then try this:
Browse to your command prompt shortcut via Start-->All Programs-->Accessories-->Command Prompt. Right click on that Command Prompt icon and choose to Run as administrator. Click Yes to tell UAC you really want to run it.
When the black window opens with your command prompt, type this in:
cdC:WindowsSysWOW64
The prompt should change to: C:WindowsSysWOW64
Then type:
regsvr32mscomctl.ocx
If you get a Window that pops up and says, "DllRegisterServer in mscomctl.ocx succeeded" then click OK and try the frontend install again.
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If you do NOT see MSCOMCTL.OCX already in C:WindowsSysWOW64 then you need to get it there and register it and then install frontend. That is the longer part of the story that I would suggest you look here http://www.hydrogenaudio.org/forums/index.php?showtopic=52353&st=0 for more info because many others have had your issue.
Read through these posts that talk about what people did to get the mscomctl.ocx file and how they made it work on 64-bit Windows (Vista in most examples there but should be similar to 7).
You could also look for a different frontend to FLAC that is not written in Visual Basic 6.0 and that works with Windows 7 x64.