Problems started after Gorbachev came to power. He made a huge mistake of rapidly introducing capitalism to the country; privatization was allowed which ended with a group of people controlling all major resources.
Not to say that capitalistic aspects of economy should not have been presented to the country, but it should not have been done so fast. If Gorbachev started perestroyka the way Lenin controlled the economy, with only very small businesses such as grocery stores, barber shops and etc being privately owned, then the merging of capitalism and communism would not be so harmful.
Speaking of imprisonments, my family actually experienced it. In the 1930's my great grand fathers on my mothers side and my fathers side were imprisoned, exiled and executed. The reasoning for that was that they recieved education in Western Europe, hence were spies; that was Stalin logic. Later on the government sent my family an apologetic note saying that they got the wrong person and increased my grandparents' pension by 25 rubles.
Yes there were imprisonments, but they mostly happened during Stalin's regime and people leaned to live with it. There was no point in hating the government, it just did what all new governmets do - make sure that there are no conspirators and whoever was even slightly thought of of being harmful was taken care of.
The biggest problem with imprisonments was that the governenet never checked if the accused person really did something. Sometimes people just told on each other for no reason and then the KGB would just arrest whoever was accused.
If you wanan know more on imprisonments I suggest you read books by Anatoli Rybakov, especially "Children of Arbat" and "35 and other Years.". Both books concentrate on Stalin's regime, imprisonments, executions and WW2 policies of the USSR.