vista service pack 2 problems

hi all just done an automatic update to install vista servise pack 2 on my acer ASPIRE 5920 LAPTOP. when update finished it asked me to restart then would start to load with loads of files flashing up then stopped at 0xc0190036 1048/46016(cryptui.dll) tried looking on mirosoft web site for help which suggested renaming cryptui.dll as cryptui.dll.old then restarted it loaded a bit further tried to rename next file but a blue screen came up with stop 0x0000c1f5 i'm in over my head now so can anyone help me please have tried system restore but that failed do not have any restore disc's any ideas please thanks

When you say System Restore failed, do you mean the process failed or it failed to resolve the problem?

If it doesn't complete successfully, try selecting Last known good configuration, see if that helps: Using Last Known Good Configuration

The Acer model you have, comes with the ability to backup your system. Did you do this? It's called Acer eRecovery Management and is a accessible via Alt+F10 at boot time. It allows you to backup to hard drive or disc.

The Users Manual for your computer is here: Acer Service & Support. The instructions are near the bottom.