I have had my MAC for around a year and half. It is a Macbook Pro with OS V 10.6. A few days ago it started taking ages to start - a grey progress bar comes up and takes maybe 5 to 10 minutes to start. Then it would be fine. I cleared out the hard-drive, freed up some space and still no better. I tried MacKeeper as said there was loads of critical errors etc. Shortly after running that I could no longer open word documents and excel files etc with office for mac. Something to do with not right edition. Now just get that encountered error and will send report. I have tried disk repair from the install disk and says cannot repair. Volume thing fine but next bit it tries and then stops repair and says it cannot do it, I should reinstall. I have most important stuff backed up - did an email back up a couple of days ago and documents etc. I am currently running a virus scan but wondering whether I should erase and reinstall everything or if it is more serious.