What does this mean? SMART Failure Predicted on Hard Disk 4: TOSHIBA MK8032GSX (S1) WARNING: Immediately back up your data and replace your hard disk drive. A failure may be imminent. Press F1 to continue. But F1 does nothing.

That's a bit of code within the drive to test itself against data corruption / hardware failure. I'd recommend using Toshiba's utility disk to test the integrity of the drive, and definitely back it up before it does fail. F1 is typcially prompted by the bios under an error state. If that's when you were prompted, then it returns control back to the boot process.

As mentioned, your machine's informing you that it's having problems reading the hard disk. You need to backup any data you don't want to lose ASAP & expect to see disk read errors in the near future...