In order to troubleshoot your problem we need to know more detailed specs of your system hardware.
1. Go to Start > Run, and type msinfo32, look under the Components section for hardware identification
2. Go to Control Panel > Device Manager and look for any entry that has a yellow flag beside it
3. The manufacturer name and model number of your PC, if applicable
4 Please fill out your computers specs in the User Control Panel here on the site as well. It will then appear next to your name. look at my posting and you'll see the drop-down arrow.
Also, was this a "clean' install or an upgrade?
Are you dual-booting with XP?
is it the official RC directly from MS?
Might have to due with Digital Rights Management.
I'm using thinkpad t400 laptop, new install to windows 7 build 7068, some song play well in windows media player 10 or media player classic..but with that same song windows media player12(of windows7) play such an error (too fast,broken..i think it may be concern to bitrate???)