Windows Sidebar Does Not Start in Windows Vista.

If when you start your Windows Vista, your Sidebar does not start automatically, here are few things you may try:

First type Sidebar in Vista's Start Menu Search bar and hit enter. It should start. Open up its Properties dialog box and ensure that Start Sidebar when Windows starts is checked. Click Apply > OK.

But if it doesn't start, you may have to re-register a related dll file named atl.dll.
To do so, click open an elevated command prompt as follows: Type cmd in Search Bar > Rt click on the cmd which is thrown up as a search result > Click on Run as administrator. In the command prompt, copy paste the following and hit Enter!
regsvr32.exe atl.dll

Furthermore, also copy-paste the following commands, one after the other, and hit enter after each one:
cd /d “%programfiles%\Windows Sidebar”
sidebar.exe /regserver
regsvr32.exe sbdrop.dll
regsvr32 wlsrvc.dll
This should resolve the issue, but if your Vista SideBar is still not starting at start up, then you may have to do a sfc/ scannow .