Unfortunately I have still not been able to reproduce this. I installed a clean copy of mIRC v7.51, using the "portable" option in the mIRC installer, in the Windows "Documents" folder, in Windows 7, 8, and 10. In all cases, the link worked.
If you install a clean copy of mIRC, using the "portable" option in the mIRC installer, into a new, empty folder in "Documents", and test the link, does it work?
