PowerBook G4- Alert Disk Full Message

[zurbert]

Last night my PB G4 started popping up this Alert Disk Full message. It is telling me to delete some things off of my start up disk. I only had about 1gb free. I downloaded some software to tell me which files are the biggest and was able to delete over 13.5gb and it is still doing the same thing. It happens when I have more than one tab open in Fire Fox, or if I have more than one application open. It is getting super annoying. Any advice on how to fix it would be greatly appreciated.
Thanks!

 

[max¥¥]

you may have a failing hdd, go into disk util and click on the hdd look down the bottom and see what the smart status is

 

[zurbert]

The smart status says it is verified. The pop ups have been showing up less frequently, not sure what I did but I'm down a full gig from last night and I have only saved 4 small word files.