First problem with Vista (Network related)
I was sitting behind my notebook and noticed that my Live Messenger keeps reconnecting. My first thought was that Microsoft have a problem with Live Services. But next day I noticed the same. I logged on XP box next to Vista one. Messenger worked. Hmmm weird... 
Problem was with Microsoft Windows Vista TCP Window Scaling and with my older release Cisco IOS which does not have TCP Window Scaling support. So the solution is to upgrade to IOS 12.3(15) or higher.
Workaround in Vista is also simple. Just run this from command prompt (cmd.exe) as Administrator:
netsh int tcp set global autotuninglevel=disabled
If you to re-enable it run this from cmd as Administrator:
netsh interface tcp set global autotuninglevel=normal
In some cases you may need to run also this:
netsh interface tcp set global rss=disabled
And to re-enable it:
netsh interface tcp set global rss=enabled
Interesting part is that I only have problems with Live Messenger and wirk Remote Desktop (RDP) not with any other IM software (Skype,), FTP transfer, HTTP transfer,...
Related:
- You may experience network-related problems after you install Windows Server 2003 SP2 or the Scalable Networking Pack (KB936594)