Acer Aspire V5 extremely slow boot up after being unplugged

Hello,

I've had my laptop for about 3 years with no issues. About 2 months ago, it just started booting up extremely slowly almost every time I tried to start it up after unplugging it, even if I plugged it in again before trying to start it up, or left it plugged in for a while before trying.

It's very problematic because I'm traveling a lot and can't leave it plugged in all the time.

I think maybe the battery is kaput, but it doesn't seem to have much problem holding a charge and I haven't noticed it draining more quickly.

When I try to start it up, the screen remains black until the log in screen appears, which again, sometimes takes hours. There's no response to F2, 9, or 10.

Any ideas or suggestions would be appreciated.

I use Windows 7. No changes to anything I can think of around the time of the issue starting.

Thanks, everyone.