Vicious

Vicious:having the nature or quality of vice or immorality.;dangerously aggressive.
Vicious circle(cycle):a chain of events in which the response to one difficulty creates a new problem that aggravates the original difficulty.;a situation in which effort to solve a given problem results in aggravation of the problem or the creation of a worse problem.
EX:As the credit crisis eats away at consumers' two biggest sources of investment -- housing and the stock market -- the risk is that more people will miss payments on mortgages, credit cards and car loans, and bank losses will balloon. It is that sort of vicious cycle that has led some economists to talk about the possibility of a depression.