could you list the microsoft Visual C++ Redistribuable package you have ? (in programs and features) ?
The 1st 5 listed below came pre-installed on my OS; the last 2 form part of Visual C++ Redistributable for Visual Studio 2012 Update 4 which I d/loaded from
http://www.microsoft.com/en-us/download/details.aspx?id=30679; that package includes a 3rd file, called vcredist_arm.exe, but as mentioned in a previous post, vcredist_arm.exe can't be run because, despite meeting the system requirements of this file, my Windows 7 service pack 1 OS doesn't see this file as a valid Win 32 application.
http://imagizer.imageshack.us/v2/xq90/661/sdb7VN.pngDo you have Antivir Pro ?
No.
I run Norton Internet Security, Malwarebytes Anti-Malware, Zemana Anti-Malware and Zemana Anti-Logger
When you right-click on opalcoin.conf and choose property: does win7 tells you it is a .conf file ?
Yes - CONF File (.conf)
is your Opalcoin-Qt folder (where you should have opalcoin.exe ) is in the "Downloads" folder ?
No, when I d/loaded the Opal-Qt-opaque.1.3.1 folder it was (automatically) saved in 'My Documents'
If yes please cut & paste Opalcoin-Qt folder on you Desk.
then, save your wallet.dat and your opalcoin.conf erase all the files and folder in C:\Users\~\AppData\Roaming\opalcoin
then paste your opalcoin.conf on it and start your wallet.
I'll do that tomorrow (it's getting late now) and post results - in meantime, many thanks for your further help. Much appreciated

I was getting this runtime error also which would cause the wallet to crash soon after opening
Installing Visual C++ Redistributable for Visual Studio 2012 Update 4 has solved my problem so far
Maybe you could try uninstalling all C++ software and reinstalling again as discussed here