As you can see, it's an XORG error. The "module does not exist" means that you don't have xf86-whatever-whatever package. mouse_drv module is provided by xf86-video-mouse. But it shouldn't be looking for it unless you specified it in xorg.conf ... I could be wrong though, I don't have nvidia nor I have used the program you use ...
It should be "xf86-input-mouse" ... Sorry.
Thanks, this moved the issue further: now what I have is: szymon@arch ~ % optirun glxgears [ERROR]Cannot access secondary GPU - error: [XORG] (EE) NVIDIA(0): Failed to initialize the NVIDIA GPU at PCI:1:0:0. Please and excerpt from dmesg: NVRM: failed to copy vbios to system memory. NVRM: RmInitAdapter failed! (0x30:0xffffffff:756) NVRM: rm_init_adapter(0) failed and from /var/log/Xorg.8.log: http://paste.kde.org/693368/ (Paste since this one is very long.) Any ideas? Xorg is black magic for me, it's logs aren't better. Thanks in advance, Szymon