[Error]Offset Error unserialize

[htbplayer]

During some testes in TMUF I noticed the following Bug in OAuth Part of the Trackmania Webservives. When i first visit the Manialink nothing appears. But after a second click through error catching the following error appears:

18.06.2012 08:46:17|Notice::unserialize() [<a href='function.unserialize'>function.unserialize</a>]: Error at offset 0 of 42 bytes|[...]inc/classes/Extended/webservices/TrackMania/WebServices/OAuth2/Client.php in Zeile: 108