Critical problems repeatedly

Hello ! Sorry for my bad English, but I'm French and can't speak English fluently ! Following several incidents (repetitive failures of my PC under Windows 8.1, first in 32 bit then in 64 bit), I found that the problems occurred during Acronis Backup worked or after he had worked. My dealer to whom I gave to fix my PC 3 or 4 times never explained me the problem and invokes viruses. My PC is protected by Bitdefender Total Security 2015 updated, plus Malwarebytes Antimalware updated. I conduct checks with RogueKiller, AdwCleaner and Sophos Virus Removal Tool. All these software can't find any problems. Unhappy about having to pay about fifty euros for each intervention, and suspecting that Acronis could be causing the problem, I uninstalled it. Since then, no more problem! What do you think about it? Thank you in advance for your response! Kind regards!
Jacques HERRENSCHMIDT