Seems your not the only one...
Another infection

Scan, clean, disinfect & quarantine any removeable devices, such as memory cards, USB drives / dongles, external hdd's. Its a nasty virus that binds itself to the autorun.inf file, so everytime you plug in or unplug a usb dongle for example, it replicates itself immediately.
Just cause its deleted from your N900, doesn't mean to say its perminately gone.
I recommend you take the following steps:-

Download Flash_Disinfector.exe by sUBs and save it to your desktop

* Double-click Flash_Disinfector.exe to run it and follow any prompts that may appear.
* The utility may ask you to insert your flash drive and/or other removable drives. Do so and allow the utility to clean up those drives as well.
* Wait until it has finished scanning and then exit the program.
* Reboot your computer when done.

Note: Flash_Disinfector will create a hidden folder named autorun.inf in each partition and every USB drive plugged in when you ran it. Don't delete this folder...it will help protect your drives from future infection.

Now download but do not yet run ComboFix
* It must be saved to your desktop, do not run it *
* Disable your Antivirus software when downloading or running Combofix. If it has Script Blocking features, please disable these as well*
* Important: Have no other programs running. Your Task Bar should be clear of any program entries including your Browser*

Once this is done rename the combofix.exe file on your desktop (lets call it george)
Double click on george.exe to start the program

* A window may open with a series of Disclaimers. Accept the Disclaimers to start the fix. Allow it to install the Recovery Console then Continue. When the scan completes Notepad will open with with your results log open. Do a File, Exit and answer 'Yes' to save changes. (The Recovery Console option will appear for 2 seconds each time you boot. You need do nothing and your regular windows will load normally. Its added in case something goes wrong so you can get on the system and fix it.)

* Caution - Do not run Combofix more than once. Do not touch your mouse/keyboard until the scan has completed, as this may cause the process to stall or your computer to lock. The scan will temporarily disable your desktop, and if interrupted may leave your desktop disabled. If this occurs, please reboot to restore the desktop. Even when ComboFix appears to be doing nothing, look at your Drive light. If it is flashing, Combofix is still at work.
Once finished re-activate your protection programs at this time

You should run Flash Disinfector on usb drives and on any others you have lying around (and then scan them with avira). Remember it's not just usb drives but cameras and ipods and anything that plugs into your usb port and has its own memory. Another program you might want to try is Autorun Eater. It stay resident and watches for autoruns.

That should fix things up