Stuck in Boot - kernel.img missing

[Gumboil]

I am using a RaspberryPi for the first time - it is a B+. I erased and formatted a recommended 8GB microsd card and downloaded the NOOBS set up from this website today. On insertion into the pi I was invited to choose an os - I chose raspbian which then installed.
The screen now goes blank with a small red square in its upper RH corner. The green led on the pi flashes regularly with 7 flashes. On re-powering the pi the colour splash occurs briefly, the screen blanks briefly, there is then a flash of a white screen followed by the blank screen with the small red square and the flashing green led flashing in groups of 7 as before.
According to the R-Pi Troubleshooting page on the linux.org website this means "kernel.img" not found - but I don't know how up-to-date this website is.
I looked at my the NOOBs downloads on my Mac but there is no file called "kernel.mg".
Please can anyone suggest how I overcome this problem.
Thank you - and Merry Christmas

[DirkS]

The screen now goes blank with a small red square in its upper RH corner

This means you have a power problem. Power supply is inadequate and / or the microUSB cable has too much resistance.

See http://www.raspberrypi.org/forums/viewt ... 28&t=58151

Gr.
Dirk.

[Gumboil]

Thank you for this. The power supply is 2000ma so that isn't the problem. I reflashed the microsd card and things are working now so obviously I did something wrong the first time.

[DougieLawson]

If the square is rainbow coloured it means undervoltage.
If the square goes red it means over temperature.

First thing to do is read the boot sticky at: http://www.raspberrypi.org/forums/viewt ... 28&t=58151