jumping and skipping dvd

[custard [uk]]

im having problems with my panasonic dvd-r.
im no newbie at this but just lately my finnished dvd's are all skipping or freezing about 1/5 the way through a film.
has any0ne else had problems like this.
im using good dvd-r's and i have cleaned the lazer. i use smart ripper then spruce up and nero to burn them>>>>>>>>?