Обновление: не удалось заблокировать / var / cache / apt / archive / lock

Я запускаю обновление (12.10 по 13.04) через терминал, и он продолжает застревать в этом:

Failed to lock /var/cache/apt/archives/lock

Что мне делать? У меня есть root-доступ. Я не знаю, что еще попробовать, кроме чистой установки.

Checking package manager
Reading package lists... Done    
Building dependency tree          
Reading state information... Done
Building data structures... Done 

Calculating the changes
Calculating the changes

Do you want to start the upgrade? 

3 packages are going to be removed. 155 new packages are going to be 
installed. 1204 packages are going to be upgraded. 

You have to download a total of 595 M. This download will take about 
1 hour 15 minutes with a 1Mbit DSL connection and about 23 hours with 
a 56k modem. 

Fetching and installing the upgrade can take several hours. Once the 
download has finished, the process cannot be canceled. 

 Continue [yN]  Details [d]y

Fetching

Could not download the upgrades 

The upgrade has aborted. Please check your Internet connection or 
installation media and try again. All files downloaded so far have 
been kept. 

Failed to lock /var/cache/apt/archives/lock 


Restoring original system state

Aborting
Reading package lists... Done    
Building dependency tree          
Reading state information... Done
Building data structures... Done 
root@chaitanya-XPS-Ubuntu:~#