IE 5.0 in Win2000Pro upgrade to IE5.1

I just installed a new Communications Server/Workstation with Win2000Pro with SP1 and it came with IE5.0 with only 56 bit encryption. The MS encryption upgrade to 128 bit encryption would upgrade it to IE 5.1… I seem to remember an article a fewmonths back that this upgrade would lock up the computer on the log-in spash screen. Has anyone had this problem ,or was it fixed with SP1?