Hi, I was wondering if anyone can help me please

I have an Acer Aspire 4520 laptop with Visa Home Premium SP1 which will only start after the second attempt. (Sometimes it starts ok)
The first try, it will get to where the little green lines run across then they stop halfway. I have to power off and start it again. It usually (but not always) takes me to a screen asking me to either Repair or Start windows normally. If I choose to repair, it does it's thing then says that the repair was unsuccessful so I've been choosing to 'Start windows normally' and its starts up ok.
This is more of an annoyance than anything but i'm worried that one day it won't start at all.

Does anyone have any suggestions on how to overcome this problem please?

The laptop is less than a year old and still under warrenty but i'd prefer not to take it back if I can help it.

Thanks
Jillann