I've had Ubuntu 11.04 installed on my Acer Aspire 5253 (64 bit) for about a month. This afternoon, it started taking about a second to recognize keystrokes. To do a key combination, I have to hold each key down for a second before pressing the next key for it to recognize it. I rebooted a few times, and it's still happening. The problem only starts after I've logged in, and doesn't occur if I log in under a new account. I haven't made any changes to the system recently, and all I've done is web browse all day today.
CPU and memory usage are perfectly normal, and everything else about the system still runs nice and snappy. I've seen a number of forum posts about problems like this, especially on 64 bit systems, but they all appear right away, while this took over a month to turn up. Any ideas what might be causing this?