I too am having this issue, I thought it may have been the skin I was using (Avalon Concept 2009 2.0.7) but even after going back to default (Standard messenger look) it still happens, its quite annoying when you have multiple tabs open. I have tried a few other skins (9.0 certified too and it happens with them all)
FYI Win Vista Ultimate 32bit
Messenger 2009 (build 14.0.8050.1202)
MsgPlus 4.80.0.356
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It appears that this happens when using anything other than Windows Aero, I was using a windowblinds skin when this happened. I unloaded the skin and went back to default Aero and it was fine. It was fine before though, so something must have changed as I have always had WindowBlinds installed as I hate Aero
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