My NOD32 v. 4.0.424.0 will no longer update the virus signature base, neither automatically nor manually. The update bar fills to 100% (shows 1/1 under the bar) then I get the error message: Undocumented serious error 0x101a Virus signature update failed." My current virus signature database is 5910 of 2/26/11. The problem just started today. The trouble-shooting link didn't help. OS is XP SP3. Thanks for any help with this problem.