Other threads describing this problem all say this read-only error occurs only when a user tries to perform a main update (e.g. from v22.214.171.124 to v126.96.36.199), however, you stated you have version 188.8.131.52 of Spybot installed which is the latest version, so your problem is slightly baffling!
I looked in my Spybot folder and couldn't find any sign of an 'advcheck.dll'. Could you try looking for an 'advcheck.dll' in C:\Program Files\Spybot - Search & Destroy?
is a hidden file. I had to log in as an Administrator, and change the settings in Windows Explorer to view hidden/system files.
In the C:\Program Files\Spybot - Search & Destroy\Updates folder, there is a file advcheck165.zip dated 11/11/2009 which contains advcheck165.exe and an .ini file. Evidently this advcheck165.exe is a self extracting executable which will update the file.
Unchecked hide hidden files, but failed to uncheck hide protected operating system files.
In my advcheck.dll's properties, the file is marked as read-only, although of course, I don't receive the error that you do.
1. With Spybot closed, navigate to your C:\Program Files\Spybot - Search & Destroy folder.
2. Go to Folder Options (Tools -> Folder Options) and in the view tab click the radio button 'Show hidden files and folders' and 'Hide protected operating system files (Recommended)'.
3. Click Apply and OK.
4. Right-click advcheck.dll and click on properties.
5. In the 'General' tab, under the 'Attributes' section, uncheck 'Read-only'.
6. Click Apply and OK.
7. Then open up Spybot and attempt to update.
8. Post back to see if this helps.
Note. It is recommended you then go back to Folder Options and re-hide hidden files/folders and protected operating system files.