cubase 7 not working anymore

get a hiss, glitchy playback anytime i try to play, from two different computers, one at home and one at studio, both doing the same thing, open cubase, get hiss sound and glitchy playback, not sure i even want to upgrade to cubase 8.5, considering how much i love the polyphonic vocal editing, and yamaha pitch correction that i cant live without, im ready to just live without it, honestly having to install first from cubase 6 DISCS, then another disc from cubase 7, then download a 5 gig file off the website to get to cubase 7.05, a whole day work just to get this glitch again on the system, is installing all these discs and downloads and upgrading to 8.5 the answer, if i upgrade to 8.5 am i going to have to install 4 different things just to use it?> am i installing this wrong, do i not need to install the cubase 6 discs anymore? desperately needing help here, if i upgrade to 8.5 can i just burn my old cubase discs, why does it seem like steinberg is forcing me to do certain things, sorry if this post seems vented but hey, im sure yall know how it is

i guess ill just answer this myself… im going to upgrade, then buy when the trail runs out, the pitch correction is too much for me to let go, and if the media browser is better that makes it even better, because reaper just added deep search…
only thing is how confusing cubase is when u try to change tempo of project mid way thru the project production, musical and timebase is very confusing