Windows – Why does the computer slow down after being on too long

It may well be one of the system services that are failing in some way.

Next time it happens you should load up the Services control panel (search: services in start menu) and check through the list for any that would relate to wireless or networking.

Some common ones to look for are:

• DHCP Client
• DNS Client
• IP Helpet
• Network Connections
• Network List Service
• Network Location Awareness
• Network Store Interface Service
• WLAN AutoConfig

There may be others specific to your wireless hardware vendor.

Go through each of these in turn and restart them (little green & black |> symbol in the toolbar). If and when the network starts working again we will have identified the culpret.

You can't do what you want because Windows always assumes there are no other non-Windows operating systems on your machine.

So long as the Windows bootloader (NTLDR or BOOTMGR, regardless) is installed to the MBR, (re)starting the machine after a hibernation will always resume from the hibernation data on disk and will not prompt you to select an OS to boot from. This is because mounting a volume that was mounted in the hibernated OS from any other OS or environment is undefined behavior. At the best case, when you then attempt to boot into the hibernated OS after mounting one of its volumes in Linux or another Windows install will detect the hibernation data as invalid and refuse to boot from it. In the worst case scenario, it'll boot from the hibernation store and there will be an inconsistent filesystem data in memory vs on disk and your volumes may be corrupted beyond repair (and I speak from experience on this one).

As such, Windows (somewhat rightly) assumes that restarting (instead of shutting down) after a hibernation is pointless, as it would simply result in the machine being in the same state it was before hibernation with nothing achieved and 5 minutes of your time lost.

Now, of course, if a non-BOOTMGR/NTLDR bootloader is installed to the MBR you can accomplish a hibernation of Windows and a boot of a different OS (though you must not modify any volumes that were mounted under the now-hibernated OS or else risk severe data loss). But Windows knows nothing of this (whether or not this is purposely ignored is a topic for another day). So the short answer is that we're trying to do isn't possible without a (para)virtualization environment of some sort.

If you're often switching between OSes and trying to go back to where you were, consider using VMware workstation or even ES(I|X) to boot into multiple OSes at once. Else, a KVM solution like the one @WillGunn suggested isn't a bad option.