Although ERIC was initially a cheery, happy computer, this changed when the Cerberus became caught up in what was essentially an interstellar traffic jam when a hyperspace tunnel closed while ships were in transit due to a build-up of geostatic pressure, resulting in the Cerberus and every ship after it colliding with each other. Unable to accept that he was responsible for the error, the Cerberus captain, Rochfort, forced ERIC to blame himself for the accident by telling ERIC that he should have overridden Rochfort's orders to try and get through the closing tunnel; ERIC was not actually programmed to be capable of such an action, but being constantly told that he should have overridden Rochfort's orders while aware that he was incapable of doing so drove him suicidally insane with guilt over his perceived failure. While the remaining passengers were offered safety in the future by the entity known as the Repulsion (Although it was really part of an elaborate trick) ERIC was left behind, ordered to spend the rest of his existence blaming himself for the accident that he could never have averted, unable to be powered down as he wasn't designed to be permanently deactivated.
By 3012, Eric had become suicidally depressed and somewhat senile, often muttering random coding errors as his programming broke down due to the psychological conflict, even as he continued to operate in the G-Lock- the space station that the Cerberus and other ships had become since the accident- as nobody was interested or able to destroy or remove him from the ship. He received his wish for death when the Fourth Doctor, seeking to defeat the Repulsion, tricked the Repulsion into transferring itself into K9, the Doctor subsequently downloading the Repulsion into ERIC and setting him to overload by short-circuiting his brain centre, destroying ERIC and the Repulsion (PROSE: Festival of Death).