It seems unlikely that Fring would have affected the way your browser works, but then again, I am not a professional Mobile developer.
The good news is that I have managed to reproduce your problem on an older version of Windows Mobile (5.0 OS 5.1.195, Build 14298.2.2.0). It doesn't let me login when I connect to the
Voxalot - Home site.
However, the mobile.voxalot.com site definitely still works OK with the same phone.
I will do some more investigation and come back here as soon as I have some meaningful information. In the meantime, I apologize for the inconvenience.
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craig