Random system paralysis in f10

Hi: I know f10 has gone EOL but I'm still running it until I 'finish' my parallel install of f12. The f10 system has the kde 4.3.3 packages from f10 updates, and I don't think I saw this problem before they were installed - but I also recently added a 1TB sdb, upgraded to mythtv 0.22 and began regular use of ProjectX under java (from Sun). Usually things work as expected, but there is a problem. The paralysis usually occurs when both sda and sdb are being accessed, sometimes quite intensively; things progressively stop working as I switch windows, and I can't shut down and do a normal reboot because several devices say they are busy. The only way out seems to be to switch off. On reboot everything has, so far, been ok, but dvb recordings that were in progress aren't properly closed. I've always had Konqueror open, with tabs showing the recordings folders on the two drives, when this has happened. Today it was apparently precipitated by opening the second tab. I'm wondering if I've hit a Konqueror bug, or if I may have a BIOS/sdb mismatch. Any ideas? Perhaps I should try Dolphin again. Thanks in advance, John P