Vista Problems with Microsoft Silver Light

Havng recieved my new xps 420 computer from dell al was running fine untill i installed Silverlight.  All was ok at first then it would randomly open loads of new tabs in Ie7 and the only way to close the IE7 would be to press ctrl+alt+del and close it down.  Then more things started happening like when i was typing in Windows live messenger the cursor would just go back to the start when i was typing each letter.  Then i went to restart windows and when i clicked the start button the start menu would just close again.  I had to press the power button and shut down windows and boot up in safe mode and uninstall silver light.

My question is is there compatability issues with vista and silverlight wit the xps 420.  Or is it something else and should i contact  dell customer servies about it.

Tracy