Grey screen and flashing question mark

I have a 13" MacBook produced in early 2008 and running Lion 10.7.5. I tried to switch it on and saw a grey screen with flashing question mark. Using my iMac I found out how to safe boot and then ran Disk Utility. Verify disk stated laptop was all right but on running disk permissions the first line stated: SUID file "System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Mac OS/ARDAgent" has been modified and will not be repaired.

I have no idea what this means but could this be the cause of the grey screen. If so, what should I do to fix the problem? If not, what elso could I do to establish what is wrong with my laptop?

Welcome to Mac-Forums..

You can ignore those errors, look at these posts to learn more.

A blinking folder usually means that Mac OS is broken/damaged/erased or any combination of those. You will most likely have to re-install it to get back in business, and hopefully you have backups of your data so you don't lose anything..

I am using the laptop in question to access this forum while it is still booted in safe mode. Does that mean (hopefully) that if I restart all should be well OR I am I likely to get grey screen again?

I have been able to use my email programme, Firefox and TextEdit in this mode.

I have not yet used the link you gave me in your reply.

If you have gotten into the system using Safe mode..then do backup important stuff first and then go ahead and re-start to see what happens..

Hopefully the disk repair fixed whatever was broken and you're good to go..

Sorry to keep bothering you but how do I back-up? I will need a step by step dummies guide.

The easiest way, if you already have an external hard drive, is to use Time Machine to backup your system. If you don't want to use Time Machine, then you can use CCC or SuperDuper to back up your entire system..

Lastly, you can always backup individual files (not really recommended)..

If you don't have an external HD, then it's a bit harder to backup. But you can still do it any writable CD/DVD you might have..

Having a good backup strategy is important to avoid losing anything valuable..

Another alternative is (assuming you have a small amount of important stuff) is to use free cloud storage companies like Dropbox, Box, Copy and so on to dump the files there until you can figure out a good long term solution..

A back up to an external hard drive using Time Machine sounds good but how big, aproximately, should it be?I don't want to buy one that is too small.

The usual recommendation is to look at how much data you have (or the size of your HD) and then double it to get a size for the external drive. Time Machine will make backups on the hour of all of your files and as the drive starts filling up, it will start deleting the oldest copy to make space for the newest..

So something like a 1TB drive should cover you for quite a while I imagine and shouldn't cost too much either..

Ashwin, Thank you for al your help.