ashDisp.exe is just an interface, the main processes you should still see running are ashServ.exe, ashMaiSv.exe, ashWebSv.exe and aswUpdSv.exe, are they running ?
Running it will make it come back but when you boot it is likely that it will be gone, that is why you need to try step 2, 3 or 4 for a permanent solution.
However, whatever it was that killed it in the first place could do the same again. What other security based software do you have that might block new startup entries, e.g. Spybot S&D (TeaTimer), AdAware (AdWatch), SpySweeper, Spyware Doctor (StartUpGuard), PrevX, WinPatrol, ProcessGuard, etc. ?