How strange, I've been running it for weeks on Windows 7 x64
Edit:
I forgot to mention, I've been using the one posted by diablosv:
https://forum.team-mediaportal.com/attachments/mp-tv-client-262/30147d1228516230-windows-64-bit-problem-mptvclient_x86.zip
Try it with that, it's v1.3.2
I can confirm that the latest v1.3.3 does not work.
Edit:
I forgot to mention, I've been using the one posted by diablosv:
https://forum.team-mediaportal.com/attachments/mp-tv-client-262/30147d1228516230-windows-64-bit-problem-mptvclient_x86.zip
Try it with that, it's v1.3.2
I can confirm that the latest v1.3.3 does not work.