I've had very little exposure to Vista but have seen similar scenarios with XP that came down to the MB battery. Loss of CMOS setup can result in Windows finding new hardware and it doesn't like when that happens. You might consider replacing the battery. Good luck.
I have a laptop, an ACER Aspire 4736 running Vista Home Premium 32 Bit with SP1. It used to work properly.
The story: One day, when I boot up the laptop first time for the day, The Startup Recovery window came up to say that Widows cannot start, probably due to a new hardware or software [there was none] and asked whether I wanted to run the Startup Repair utility. Indicated Yes. It found and repaired the problems and Windows Vista was able to come up, and the laptop worked normally... I then shut down the laptop.... In the afternoon,some 3 hours later, I tried to start up the laptop, but it won't, giving the Start up Recovery Window again.... I have to run startup Repair and the laptop worked normally again... As an experiment, I shut it down, wait 15 minutes and tried to start it up...Lo and behold- that Startup Recovery window came up- however, this time...start up repair was not able to do the repairs, and Windows did not came up. The next day I tried to startup the laptop, which successfully booted Windows the first time despite the problems the previous day...and if I shut down then restart later in the day....I won't be able to...and the events recycles....
I have tried to duplicate successfully the above events for several days. The laptop always booted to Windows without problems 1st time the next day...
Thinking that there were corrupted system files...I reinstalled Windows using the built -in utility but to no avail. The same events occured... I used the Recovery discs [created when 1st using the laptop, as advised]. No solution. Same chain of events.
What is strange is : Why was the laptop able to boot up normally the next day, despite having unresolved booting problems the day before ?
[The "Startup Recovery" and "startup Repair" are built in utilities, probably came with Vista, or provided by ACER]
Thanks for any ideas.