My wife's Macbook Pro only opens in Safe Boot mode, will not recognize her password or Installation disc. In Single User mode, I cannot type fsck -fy at command line to check hard disc because keyboard only produces caps, not lower case. Help?

Thanks for your advice, Marek, but I'm afraid it doesn't help. When the Macbook is powered up, it just opens to a dialog box showing 'Safe Boot Mode' in red, with a space below for a password. When the correct password is entered, the box vibrates and refuses to accept it.

Following the advice in Apple Old Article 106214, 'Try Disk Utility', I tried to start up from the Installation disc, but when the disc was inserted in the DVD drive, nothing happened. The Safe Boot Mode message was still there, waiting for a password.

Again following 106214 'Use fsck if necessary', I started up in Single User Mode by holding down the Command and S keys at the same time. I got the command screen OK, but when I tried to enter /sbin/fsck -fy as insructed, I could only enter ?SBIN?FSCK -FY. I tried entering other letters in lower case, but could only get upper case.

I can't check if the Macbook Shift key is stuck because I can't type anything anywhere except at the command prompt. I can't access Applications>Utilities>Terminal because I can't get past the Safe Boot Mode dialog box. The Macbook is quite new (bought in March 2011 in the USA), and we have not had any problems with the Shift keys before.

I've seen the same problem discussed on the web, for example at http://www.justanswer.com/mac-computers/4z0ot-mac-osx-just-rebooted-itself-says- safe-boot.html, but the final advice from the expert was to visit a Genius Bar. I live in Portugal, where we have resellers but no Apple Store, so I thought I would try the Apple Support Community first.

(I'm using my own iMac for this message, not the problematic Macbook, of course!)

Been away for a few days ... yes, you are right, what appears at the commend line is FSCK_FY, not FSCK-FY. So the problem seems to be connected with the Shift function. I tried repeatedly pressing the Shift keys without effect. I don't have a compressed air can at the moment, but will try that also. Thanks for the comment.

As I mentioned earlier, when I insert the Install disk, nothing happens, so I can't go to System Preferences or anything else in the OS. I'll call Apple Support and report back if they can provide a solution. Thanks for the suggestion.

I spent more than an hour on the phone to Apple Support; finally, the man I spoke to recommended reinstalling Snow Leopard from the original startup disk. I did this; nothing happened. Playing around with the keyboard in frustration, I discovered that if I hold down the Command key while restarting, the computer opens up with the norrmal desktop, and I can access all my programs, Mail, Safari and the Internet - EXCEPT that I still can't type in lower case. In MS Word I can change text typed in all CAPS to lower case using Format - Change Case (or the appropriate keyboard shortcut), but that's all. If I restart the computer without holding down the Command key, it opens in Safe Boot mode again.

I've had to set the problem aside for a couple of weeks due to other pressures, but this next week I'm going to take the Mac to the service desk at our local reseller to seee if they can fix it. It seems to be a fairly common problem, judging by the number of references you can find through Google, but I haven't found any mention of a solution.

Meanwhile, my wife had to buy a new Windows machine to be able to finish a major job for an overseas assignment ... (I'd only finally converted her to Mac earlier this year, after years of trying!).

Let's hope the guys at the local service desk can solve it. If they do, I'll post the solution here.

Thanks to roryfrommitchelstown and ndog21, but I'm afraid I haven't got any further. I don't have a separate keyboard available; did using it solve the problem once and for all - i.e. after shutting down and restarting, were you able to use the regular keyboard and log in normally without the Safe Boot/password problem? If so, I'll ask the guys at our local service centre to do that. If not, we still need to find a permanent solution; no point in having a laptop and having to carry an extra keyboard around in order to use it.

I'm not sure what ndog21 means by 'boot in to recovery HD'. I found that holding down the option key works the same as the Control and Command keys, i.e. the regular startup screen appears and I can do everything except type in caps. But the only 'recovery HD' I have is my Time Machne backup drive, and to restore the entire system from that I have to insert the install CD and click on 'Utilities" and then ... enter my password! Which is not accepted because it is presumably all in caps.

I'm going to the service centre tomorrow (Friday 7 October) and will report back. Thanks for your help anyway.

Took the Mac to the service desk on Monday 10 October. The guy on the desk spent 45 minutes on it, but couldn't solve the problem. I left it with him to be sent to their lab for a more thorough check - may take up to 2 weeks!

Just got the Mac back from the service desk. It had been sent away (I suspect, outside Portugal) and came back in full working order – but Apple had to replace the entire keyboard. So it does look as if it was a hardware problem. Maybe there was a faulty batch in production which i why quite a few people have reported this problem. So, no quick fixes, it seems; take your Mac back to a service centre!