A big problem with computing in space is the radiation environment. To be quite frank, it's absurdly hostile. IIRC the voyagers have very little computing power (so, few things that can malfunction) and even then they run three processors that are already radiation-hardened, and each computation is run in parallel on each processor, and the outcomes are compared among the three to detect and throw away any computations that were altered by radiation-based bit flips.

Such is space. Everything needs to be designed specially for it, especially for trips beyond LEO (where the magnetosphere is still providing you significant protection).