Check if you have installed any helpers or add-ons to your explorer. Uninstall them. Often, even 3rd party shell extensions can cause Explorer to crash on particular actions. Several programs add items to the right click context menu. Download freeware utility ShellExView. It will let you view & disable suspect 3rd party shell extensions. ShellExView can be also be used for solving contextmenu problems in Explorer, like, say, if the Right-click is slow.
If it doesnt help, then for more options see Windows Vista Explorer Crashes Frequently.