Wierd Burning Problem With Ricoh7200a burner!

Hello!Lately my computer (AthlonXP 1800+,Asus a7v266,Geforce2PRO,Maxtor40Gb@7200,Audigy DE)startedaking trouble with burning.It goes like that:I start burning with Nero 5.5.10.0 and at 60-70% the hd starts mumbling,the buffer gradually goes all the way down and burning process stops.After couple of seconds it gets filled again,and burning resumes(thanks to JustLink).I dont get coasters,but the burning takes more time than usual.The burner works at udma2,hd@udma5.The problem exists in clone 4.2.0.2 too.HDD defragmented,i dont run programms while burning.The burner worked fine till now…
Any suggestions?