Alternatively, you may download just the file you are missing and manually register it yourself. Here's how to do it:
Download MSWINSCK.OCX (right click the text on the left and save to your Desktop).
Back up your current copy of MSWINSCK.OCX and copy the new version to the same file location. This file should be located in the WINDOWS\SYSTEM directory on your C: drive (for Windows NT and 2000: \WINNT\system32).
Using your mouse, click on the "Start" button and then click on "Run".
According to your Operating System, type the following command to register this library file:
Windows 95, 98, or Me:
regsvr32 \windows\system\MSWINSCK.OCX
Windows NT or 2000:
regsvr32 \WINNT\system32\MSWINSCK.OCX
Windows XP:
regsvr32 \windows\system32\MSWINSCK.OCX
You should see a message saying "DllRegisterServer ... succeeded"