restart on cleaning registry

iono y it always restart when i tried to clean the registry. i made a restore point as the very first date. and i also tried to reformat the pc it still the same. does any1 kno how to fix this and y it happen? plz help me fix this... i don't want a slow computer. i also check for virus and spywares. no virus but the spywares are cookies. however, i use spyware doctor to remove all those spyware cookies but it won't. those are the problems i'm most facing everyday.

 

how are you trying to clean the registry
with a program ?
if so which one ?

 

i tried to clean it with tune up and registry mechanic... also when i open commad prompt it restart too.