Startup Shutdown probs

I go through the same routine now whenever I boot up. The first time it freezes. The second time is offers me safe mode or normal mode. I select normal and it freezes again. The third it offers me the choice again. This time when I select normal it works perfectly (although slowly).

Once booted the computer works fine.

Shutdown also rarely goes well.

I've been told by friends to reload ME. Is there any anything else I can try before taking that step.

I think my problems started when I installed a netgeat USB adapter.

Thanks.