Earlier today my N900 was freezing and refusing to play music and open applications, the wallpaper wouldn't load or change and my icons and widgets kept resetting themselves after a restart. I reflashed the firmware and it's still doing it. What do I do?

did u just flashed the kernel or also flashed emmc ?

I only flashed the kernel. The instructions for flashing the eMMC looked very confusing. I do have the RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin downloaded if someone could explain how to flash it and the whole thing about flashing the "FIASCO/rootfs image" I don't want to end up bricking my device.

flashing emmc is not that hard dude. here is the procedure:
firs flash ur kernel and then flash emmc image.
copy and past this code in cmd windows to flash emmc image:

check this THREAD for more info on flashing ur phone.

Just a side question, did you overclock your device? Also (since we can,) mind opening up the terminal and typing in "dmesg" and posting it if possible?

if my emmc image name is different with one you have replace the name with ur emmc image name file.

if you want to flash your eMMC then put your eMMC images files on maemo/flasher-3.5

now open flasher then type.....

after RX just use TAB button then it will automatic detect your eMMC images on flasher folder....once you have detected the eMMc images then just completed the command by adding....

at the and....remember adding just -f will not reboot your device...adding -f -R will reboot your device after flashing....
also i suggest for a clean device re-flash your eMMC first then your fiasco images....do not reboot between flashing eMMC & fiasco images but you can added -R at the end of flashing fiasco images command to reboot after completing flashing your eMMC + Fiasco images...

Gah. I executed the command and then plugged in my N900 while holding U and this is all I got.

Anyone? I need this damn thing tomorrow :c

which version of WIndows are you using?

AFAIK the flasher doesn't work on Vista/7 64-bit.