Where is my DNA? - Am losing my stored at -20 Degrees... (Mar/16/2005 )

Hi guyz... some1 is stealing my DNA!!!!! For digesting I use the Vector stock. After digestion I find no DNA in my gel!! (I digested with Eco RI and Sal I in NEB buffer 3, for 3 Hrs at 37 Degree C.) What could be the possible reason ? Even the DNA which I had stored in -20 are not visible now!!! they are completely gone!!! PLz help where should I be more cautious?
Thank you

what buffer do you store your DNA in?