iTunes songs when loaded to Sansa Clip results in an artist "Unknown"

I needed to convert some songs (none were purchased) in my iTunes library from AAC to MP3 to load to a brand new Sansa Clip. Rather then destroying the integrity of that library, I created a new library and opened it. I did an import (FILE|IMPORT) of some songs (only one artist). I selected all the songs and converted (ADVANCED|Convert) the selection to MP3. My library contained both AAC Audio files and MPEG audio files. I deleted the AAC files thus leaving the library with songs with MP3 extensions.

[Chris suggested I do the following: To save time, instead of File -> Import then import, then convert, then delete, do this...In the new library, hold Option then menu Advanced -> *Convert selection to MP3* {or whatever is in iTunes prefs - Advanced - Importing}. This will convert the songs on importing and only the new format will be in the new library.]

I connected my Sansa. I copied all the songs to the Sansa's Music folder. After I ejected the Sansa, I opened the Artist selection. My artist and songs were there and I could listen to the songs. I did notice in the Artist list a name of Unknown. It contained only the song titles without audio content. When I called SanDisk technical support I had to escalate my problem to a senior technician. He is now researching it. He is thinking it might be a bit rate. Anyone have a fix for this?