CMS Made Simple Forums

Hello. I imported around 600 users and additional properties into FEU. Not all users filled out all properties so I removed the empty values and imported all properties with ascending uid's. When I try to edit a front end user's properties from the backend I get this notification:
Error

Some empty values in the fields have been filled by the text 'input_' and the name of the field (so 'input_streetname' for example). Would the problem be that there are properties with no db-id attached to them?

CMS Version
1.8.2

Installed Modules
CMSMailer
2.0
FileManager
1.0.2
MenuManager
1.6.5
ModuleManager
1.4
News
2.10.6
nuSOAP
1.0.2
Printing
1.1.0
Search
1.6.5
ThemeManager
1.1.1
TinyMCE
2.7.2
CGExtensions
1.21
JQueryTools
1.0.9
CGSimpleSmarty
1.4.5
CompanyDirectory
1.7.2
CGCalendar
1.5.6
FrontEndUsers
1.12.8
CGUserDirectory
1.2.4
NMS
2.3.2
SelfRegistration
1.6.7
CGFeedMaker
1.0.11

Any help would be greatly appreciated!

OK, I'm making 'some' progress.

I started out importing only the user data straight into the DB (feu_users) with CSV files out of Excel. Then I tested a couple of users to see whether I could save some properties. This worked.

After that I started importing the properties, one property at a time (eacht user has about 20) for 600 users. After the first import all was good. After the second one the error notification returned. I decided to do an export of the data via the Admin window of FEU. After examining the file in TextEditor I uploaded it again via the FEU import module. This gave 190 errors (out of 600) so I decided to look up some of the conflicting lines using JEdit. I couldn't find anything alarming so I decided to save the file in JEdit and upload it again. Now the last import isn't throwing errors.

So I guess it has something to do with the formatting of Excel. Now I'm gonna start reformatting all my data to import it into the DB.

Fixed. Apparently it had something to do with aforementioned formatting. Also some malformed fields.
Tip: import your data in small bits so you can identify errors. I just spent 4+ days learning it the hard way.