Does UPS cause PCs to hang?

Our UPS (Uninterruptable power supply) was purchased when we had about 100 computers and a main frame with about 30 terminals. Now we have about 300 PCs and 100 terminals. The PCs hang(Not responding) message if you alt-ctr-delete after failing. Could the UPS be the cause of this phenomena or poor quality (IBM 300GL & PL) Pcs made in China and Taiwan as well as Malaysia? Am calling from Kenya, Eastern Africa.