Startup slowing problem with Vista h.e.

After working out which program had caused some performance problems*
with my Toshiba Equiuum laptop - Kontiki, used with an on-demand tv
program for Channel 4 in the UK - I reinstalled Windows. Unlike a
previous occasion of doing this to get rid of all trace of Norton,
startup has slowed down, in fact it seems to pause, and had done right
from the start of the new install. How can I sort this out? I'm
puzzled as to why this should happen when I used the exact same method
and Recovery Disk, supplied by Toshiba.

I've looked at Task Manager to see if I can see where it's stalling
but I can't tell. I had to uninstall Norton again as it's loaded from
the Recovery Disk but the stall was happening regardless of this.
Anything involving the Software Explorer bit of Windows Defender?

I thought it might be the Sidebar but it's not that, and this had all
worked fine before anyway.

I had the terrible thought that Recovery Disks only work a finite
number of times in order to get people ot pay for a copy of Windows.

*The performance 'problems' were possibly nothing serious or
noticeable, just me reacting to an exclamation mark in a yellow
triangle, but it niggled me and I thought it might get worse as other
software was added etc.

Thanks in advance for all input. I'm reasonably computer literate but
if anything might need explaining please err on the side of caution.
Thanks.