I have a cheap multimeter that used to work fine but now it has negative readings — even when the leads aren't connected. I changed the battery, looked for a blown fuse but no luck.
Any idea what's going on? Is it toast? It's a GB Instruments GDT-11.
Replace multimeter with a reputable brand. Depending upon your application and needs, you can either go for a cheap multimeter or an expensive one like Fluke, Agilent, etc.
Occasional and hobby use: Buy a cheap one from RadioShack. Further, if not measuring high voltage, get one from Harbor Freight for < $6.
Professional use: Buy your equipment from Fluke, Agilent, etc. Equipment from reputable manufacturers will give you peace of mind, ROI on the equipment, reduced liability if you have employees, accurate measurement, etc.
Beware, do not trust a cheap multimeter for high voltage measurements. Review and verify the CAT rating on the multimeter if you frequently measure high voltages.