This behaviour means that there is a program or driver loading in normal mode which is affecting your loading process. From safe mode, review your installed programs (control panel, Programs & Features) - uninstall anything you don't need or looks suspicious. Also try the System Configuration utility (Start button, type 'msconfig' in the search box). On the start-up tab deselect all items. If that works then you can begin reinstating them one by one to find the culprit.
If neither of the above help you can try a system restore.