vista problems,all here

Eu got a big problem in my pc.First of all,i give my system´s properties and
also i have to add that i recently had installed ubuntu desktop edition in my
notebook.
HP pavilion dv6500,Intel(R) Core(TM) Duo CPU,T7300 @ 2 GHz 2 GHz,RAM
"GB,wondows vista 32bits
The problem i got is it´s first of all (vista) work more than normal and
sometimes without objective!!!While when i work with ubuntu it works without
problem.So,the problem is not with my notebook but yes with vista.And lastly
has appeared 5 time the famous Blue Screen.
and for example when i close my firefox also had saved some new settings
when i restart it i see that new setting are not working.please don´t tell me
that the problem is with firefox because i got other operative system in home
which is xp and i don´t got this problem.another example is my norton360
which i had installed recently and one of blue screen erro happende during
his installation.and after reinstalling it ,now there some items in settings
to fix which i can´t!!but after restarting yeah!it workes!?.
I would like to know what´s goning on?I has installed all vista updates.I
had defragmented my sytem and etc.I want to know that if i have to format e
reinstall vista everytime i want to use it!
About security it's more funny.I would like to have solution to this also.I
had downloaded the ubuntu desktop edition then i burnt it to cd.After that i
boot my notebook with this cd.without installig it,using live cd,i worked to
ubuntu and i also get access to my windows drive and consequently to my files
wihtout any permission.so what's going on?Have i encrypte my all files!?so
what's the logic to put user password.
I'm waiting for an answer