clicking Explorer pops Windows Installer window

Recently I found I cannot run .msi files any more, so I searched windows.bbs and got the solution by updating MSI with WindowsInstaller-KB893803-v2-x86.exe. My system is winxp pro Chinese simplified and I got the update file from the Chinese website of Microsoft. After updating MSI, I am able to install msi files just by double clicking on those files. However, a more serious problem occured after that: whenever I click on explorer.exe or any shortcut thereof (like the ones in the Start menu, the My Computer Icon on desktop and Recycle Bin, or even IE), a Windows Installer pops up which shows the words "Preparing to install..." (literally in English, even my system is a Chinese one!), and it hangs for around 1 to 10 minutes before explorer window comes up. I searched several places on the net, including this bbs, for a solution but with no luck. Could anyone please give any clue to solve this? Thanks a lot.

 

That doesn't help. However, the problem seems to be solved by HijackThis (the problem was some missing files which are expected as Explorer plugins. Perhaps my anti-virus program accidentally regarded them as virus or adware and removed them).

By "seems" I mean that now clicking Explorer.exe is now working perfectly, but clicking .msi files would only silently install the file without showing any dialogues (No license information shown, no chance to choose installation destination and no chance to change one's mind to cancel the installation, etc). Never seen this strange behavior. Installing all available windows update didn't help, reinstalling Windows Installer didn't help either. What is even worse is that while testing the behavior of the windows installer, I accidentally have chosen a file boundled with some Hook-Ware called Baidu Search Accompany, which I struggled whole night to remove but without luck. This time even HijackThis wouldn't help: HijackThis can found the registry keys related to Baidu, but cannot remove those. Sigh...