As I have been exploring Windows 7 RC1 for quite sometime now. I hit upon this rather dangerous news, for all you folks out there who are running Windows 7 (irrespective of the builds - either Beta Build 7000 or 7048 or 7057 or recently leaked Build 7068) on a Lenovo T60p, Lenovo T61p and all HP portable machines are at a very high risk of Data Corruption.
Microsoft has recently warned that testers of Windows 7 could come across data-corruption issues on various machines including computers from Lenovo and HP. Data Corruption is the worst thing that can happen to you - coz you'll have bits and chunks of your data and most probably that data might not be useful as it may not open up at many times.
According to Microsoft the problem lies with the Offline Files service and the Client-Side Caching (CSC) driver, which fail to work together. Users running Windows 7 on Lenovo T60p, on Lenovo T61p, and on HP portable machines are at a very high risk of having their data corrupted. Both the 32-bit and the 64-bit variants of Windows 7 Beta Builds were affected.
But luckily, Microsoft is currently offering a hotfix designed to resolve the issue. the hotfix can be found here.