How long can I leave my computer on? I have just recently gotten acquainted with a file-sharing program called Bearshare, and being able to leave my computer on 24/7 would really help in accessing certain rare files. I’m just wondering; is it safe? If it’s not ok to leave it on 24/7, how long can it be on?
I just had this horrifying flashback to Sir Laurence Olivier, leaning over with a whirring dentist’s drill . . .
Is it safe???
I run them until I need to stop for some reason; i.e., months at a time.
Mine stays on until Windows causes it to crash - which is about every hour when I’m using it. 
Yeh, computers can pretty much stay on indefinatly, or at least until the OS packs in (usually within 24 hrs if your using windows 95/98/98se), in which case a reboot is in order.
I know very little about home computers, but I’m gonna go ahead and parrot what I’ve heard on Screen Savers over and over again: if your computer is always on and connected to the internet, you should install a firewall. Otherwise, you’ll git yerself hacked, and naughty twelve-year-olds will use your machine to launch denial of service attacks on nice websites, or do G-d knows what else.
As long as you want. It’s been suggested that leaving a computer on is actually better for it, as the constant cycle of powering up and down, heating and cooling etc shortens its components’ lifespans. But I suppose it depends on how often you use it. I know that when something eventually breaks it’s usually with the surge of power when switched on.
Either way, unless you’ve got sub-standard equipment you’re more likely to find your computer will become obsolete before it wears out, even if left on continually. Same goes for the likelyhood of it being dangerous or causing a fire or something.
The deciding factor is, of course, the cost and energy efficiency of leaving it on all the time. If you’re going to do it you should at least get into the habit of switching off the monitor.
There is generally not a problem with leaving your machine on or connected all the time. You should turn the monitor off when you’re not using it though because monitors are generally energy hogs. As Podkayne recommended, a firewall is definitely worthwhile for an always connected machine.
Now the bad news, Bearshare has a problem – it has been reported to the developers and they should be working on it but it hasn’t been fixed as of version 2.7. I don’t want to go into unnecesary detail but the result is that after Bearshare has been running for a while, other Internet enabled applications will be unable to start and you’ll get a message that says “Insufficient Memory” or words to that effect. The upshot is that regular reboots are essential when using Bearshare. How regular depends on your particular system.
Also be advised that Bearshare is considered spyware.