This is a fragment from a mail I sent to someone who also didn’t have any gadgets in his list and also an empty sidebar:
Download and start the tool Process Monitor, first disable the monitor by clicking the magnifier in the toolbar, then erase your logwindow. Make sure SideBar.exe is shut down and that you can open it quickly via a quick lauch click or something. Now click the magnifier again so the logging will start. Now start your sidebar and wait till it has fully started up. Switch to the Process Monitor window and click the magnifier to stop monitoring.
In the menu filter click filter CTRL+L and add the following line:
Process Name | is | sidebar.exe | include
Next click OK to apply the filter. In the main window you have a column Result. Try to lookup if somewhere trying to read a file, the file is missing; checking a key in the registry, the regkey is missing etc. Simply all entries without the resultcode SUCCESS.
If you have enough technical experience or want to learn something you should check this out!