The software update may fail if there's not enough free space on the phone memory (C: drive). The phone memory should have at least 8 MB free space.The current consumption can be seen by selecting Menu > Applications > Office > File Mgr.
If there's not enough free space, release some data for example by checking the following:
- When installing additional applications, install them to the mass memory (E:) instead of phone memory.
- Make sure that photo and video storage is on mass memory.
- If there's still not enough free memory, you can set the message saving location to mass memory by selecting Menu > Messaging > Options > Settings > Other > Memory in use > E: Mass memory (this is, however, not recommended if there's any other means to release memory).