Norton Internet Security 2004 OEM Version

I have just installed the above and it has seriously slowed down the computer when booting up, it is taking over ten minutes. I have looked at the Symantec Web site but cannot find a fix.  Short of taking it out of start up has any one

any suggestions. Computer is a Dimension 4100, Pentium 3,  OS Windows 2K professional 512 Ram.

Also one particular site which has a message board and facilities for posting pictures has the pictures blanked since I installed the Norton, this does not seem to happen on any other web site we access.

Moiran.