恢复win2003，dotnet又出了这个问题，有个blog的解释如下:
这一般是安装了双系统的原因,windows installer发现TLBs 和DLLs已经存在,就不再注册,可以通过调用控制面板中的vs.net安装程序,选择2中的修复,就可以了. 可以参考MS Support Q320427.
查了一下msdn，原因不是由于双系统，而是由于多次安装，tlbs，dlls存在引起的，我的双系统是win2003，suse linux，
把q320427引用如下：
PRB: "VC Package Not Available or Not Registered" Error Message
适用于
This article was previously published under Q320427
SYMPTOMSWhen you create a WinForms application, you may receive the following error message:
"VC Package not available or not registered" This behavior can occur even after what appears to be a successful installation.
CAUSEThis behavior seems to occur because the Windows Installer does not register TLBs and DLLs if the installer finds that these items already exist. In most cases, a previous version of Visual Studio .NET causes this behavior, even if the previous installation was under a different operating system.
RESOLUTIONTo resolve the problem, run the Visual Studio .NET repair. A repair is more effective for fixing this issue because the repair process forces registration of items that are not re-registered during an install.
To run the repair, follow these steps:
On the
Start menu, point to
Settings, click
Control Panel, and then click
Add/Remove Programs.
On the list of installed programs, click
Visual Studio .NET, and then click
Change.
Click the second item in the
1 2 3 Visual Studio Setup dialog box.
Click
Repair/Re-install, and then follow the onscreen instructions.
MORE INFORMATION
Steps to Reproduce the BehaviorTo reproduce the problem, it is best to have two operating systems installed on separate partitions. Two installations of Windows XP Professional will work.
Install Visual Studio .NET under one operating system.
Install Visual Studio .NET under the other operating system; change the default location to match the installation location of the first installation.
Both installs report as successful.
Start the copy of Visual Studio .NET that you installed in step 2.This type of installation is never recommended. Even if the installation selections are exactly the same, and you can save disk space by performing this type of installation, the potential for problems is high. If one installation changes files and registry entries, these changes are not recorded by the other installation, which creates a substantial risk for unexpected results.
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