You can control what errors pop-up to interupt you by using the following registry keys (errors are still recorded in the event logs):

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows

Add value NoPopUpsOnBoot as a REG_DWORD. When set to 1, Boot pop-up messages are suppressed. The default is 0.

Add value ErrorMode as a REG_DWORD.
0 - All system and application errors Pop-up (this is the default).
1 - Errors from system processes are suppressed.
2 - All system and application errors are suppressed.