Raspberry Pi power supply is widely misunderstood. A lot of the problem is because of improper power supply. A power supply that can provide 5V and 1A is good enough. However, if you are planning to use a WiFi USB adapter other than what I had suggested, try using a 5V, 2A power supply, which can help Raspberry Pi run more stable.

There are five LEDs near the USB connector. The status of these LEDs can help interpret the problem with a Raspberry Pi:

Raspberry Pi does not respond to keyboard/mouse.

As mentioned earlier, most of the problem with Raspberry Pi is because of the inadequate power supply. In this case too, try using a good power supply and good cable. Some cheap cables that work with a cell phone cannot fully power the Raspberry Pi. There are USB devices that require more power. Check the voltage and current rating of the devices before connecting it to the Raspberry Pi USB port. If it is more than 5V 100mA, it is better to use USB hub to power such devices.

You can use the following command to test your webcam with Raspberry Pi and change configuration settings if required:

sudo apt-get install guvcview

Based on the camera, it might work with an internal USB port only, not with an external USB hub.

Ethernet connects at 10M instead of 100M.

In rev.1.0, the LED corner is mislabeled with 10M instead of 100M. When that LED is ON, Raspberry Pi is connected to 100 Mbps.

The Ethernet connection is lost when any USB device is plugged in

The Raspberry Pi USB ports are configured in such a way that it can provide 100mA current to both the USB port. However, if you try to connect the USB device, which requires more current (>100 mA), then connect it using a powered USB hub.

Sound does not work with the HDMI monitor. This is caused by some computer monitors that select the DVI mode even if an HDMI cable is connected. This is required even if the other HDMI devices work perfectly with the same monitor.

Add the following line to the configuration file, /boot/config.txt:

hdmi_drive=2

The preceding line of code will force it to select the HDMI mode.

Sound does not work in some applications.

The Raspberry Pi OS also comes with drivers installed by default. However, to install support for sound, enter the following command in your command line:

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install alsa-utils
sudo modprobe snd_bcm2835

Try entering the following command to test whether sound is working or not:

aplay /usr/share/sounds/alsa/Front_Center.wav

The camera board requires 250mA to operate. Make sure your power supply can provide enough power for the camera module as well as Raspberry Pi, and any peripherals directly attached to Raspberry Pi.

If you just get errors instead of a desktop, when typing startx, you may be out of storage space on the SD card. gparted can expand a partition, if the SD card is less then 2 GB. Expanding the partition will solve the problem.

The kernel and firmware are installed as a Debian package. These packages are updated infrequently after extensive testing. You can use the following command to update the Raspberry Pi firmware:

sudo apt-get update && sudo apt-get install rpi-update

The Raspbian wheezy image (as downloaded) only uses the first 2 GB of space on the SD card. There are two options. You can use the Raspi-config GUI to resize the disk or you can do it programmatically. The expand_rootfs menu item reconfigures the operating system to use all of the space available on the SD card. A restart is required to make the reconfigure take effect, as shown in the following image:

These are the steps to manually resize the disk: