[arch-general] Problems with mouse and keyboard on X

Hello, I am new to archlinux, coming from gentoo, and have successful installed the system so far. Now I have the problem that when I start X by using startx or startxfce4 (I have only tried this two) I have no keyboard or mouse. I can solve the problem by disconnecting and reconnecting mouse and keyboard. After that everything works fine until I restart my computer. To rule out problems with access rights I even used startx as root, but the same problem exisits. I suspect that something is wrong with udev (as I use evdev for mouse and keyboard) but so far I am not able to locate it. Has anyone some idea or lead for me? Greetings Sebastian Beßler