I'll vote for 12h-24h since I've been basicly monitoring my gateway every 5 min. (Inc. my virusses) for a couple of hours yesterday, to find myself taking an 45 min. break, coming back, my spyware gone meaning I''ve lost control over all the adware on there (Long story why there's spyware on there not going to explain)
Thanks to help of somebody who logged on and disinfected the spyware I now can collect my adware, but it was annoying as hell since there was also other peoples adware on there
Oh and where about does that warning come that they're taking over? I haven't seen any big bright red flashing letters
VIRUS BEING TAKEN OVER! now that would be clear