WinXP pro & webcam freezing

Upgraded PC from WinMe to Win XP Pro & now webcam freezes after 5-10 seconds. Tried using Logitec software and Windows Movie-Maker software with same effect. It’s a Logitec Quickcam Pro, but I tried another Logitec cam & it froze the same too. Off I went to Logitec & got the latest XP driver & installed it – still freezes. Both cams work OK if hooked up to my other PC running same OS. Any ideas folks?? Thanks.