o.k i got the error a bit more precicely. some kind of sql error.

ERROR:Error 256: DATABASE ERROR: Couldn't run query: SELECT `Member`.*, `Member`.ID, if(`Member`.ClassName,`Member`.ClassName,'Member') AS RecordClassName FROM `Member` INNER JOIN `Group_Members` ON `Group_Members`.MemberID = `Member`.ID WHERE (`Group_Members`.`ID` IN (SELECT `ID` FROM `Group_Members` WHERE `GroupID`='1' GROUP BY `MemberID` HAVING MIN(`ID`))) AND (`Group_Members`.GroupID IN (1)) GROUP BY `Member`.ID ORDER BY Surname, FirstName LIMIT 0, 10 | You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT `ID` FROM `Group_Members` WHERE `GroupID`='1' GROUP BY `
At l431 in /homepages/28/d30331995/htdocs/test/sapphire/core/model/Database.php
user_error(DATABASE ERROR: Couldn't run query: SELECT `Member`.*, `Member`.ID, if(`Member`.ClassName,`Member`.ClassName,'Member') AS RecordClassName FROM `Member` INNER JOIN `Group_Members` ON `Group_Members`.MemberID = `Member`.ID WHERE (`Group_Members`.`ID` IN (SELECT `ID` FROM `Group_Members` WHERE `GroupID`='1' GROUP BY `MemberID` HAVING MIN(`ID`))) AND (`Group_Members`.GroupID IN (1)) GROUP BY `Member`.ID ORDER BY Surname, FirstName LIMIT 0, 10 | You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT `ID` FROM `Group_Members` WHERE `GroupID`='1' GROUP BY `,256)
line 431 of Database.php

Database->databaseError(Couldn't run query: SELECT `Member`.*, `Member`.ID, if(`Member`.ClassName,`Member`.ClassName,'Member') AS RecordClassName FROM `Member` INNER JOIN `Group_Members` ON `Group_Members`.MemberID = `Member`.ID WHERE (`Group_Members`.`ID` IN (SELECT `ID` FROM `Group_Members` WHERE `GroupID`='1' GROUP BY `MemberID` HAVING MIN(`ID`))) AND (`Group_Members`.GroupID IN (1)) GROUP BY `Member`.ID ORDER BY Surname, FirstName LIMIT 0, 10 | You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT `ID` FROM `Group_Members` WHERE `GroupID`='1' GROUP BY `,256)
line 108 of MySQLDatabase.php

MySQLDatabase->query(SELECT `Member`.*, `Member`.ID, if(`Member`.ClassName,`Member`.ClassName,'Member') AS RecordClassName FROM `Member` INNER JOIN `Group_Members` ON `Group_Members`.MemberID = `Member`.ID WHERE (`Group_Members`.`ID` IN (SELECT `ID` FROM `Group_Members` WHERE `GroupID`='1' GROUP BY `MemberID` HAVING MIN(`ID`))) AND (`Group_Members`.GroupID IN (1)) GROUP BY `Member`.ID ORDER BY Surname, FirstName LIMIT 0, 10,256)
line 81 of DB.php

DB::query(SELECT `Member`.*, `Member`.ID, if(`Member`.ClassName,`Member`.ClassName,'Member') AS RecordClassName FROM `Member` INNER JOIN `Group_Members` ON `Group_Members`.MemberID = `Member`.ID WHERE (`Group_Members`.`ID` IN (SELECT `ID` FROM `Group_Members` WHERE `GroupID`='1' GROUP BY `MemberID` HAVING MIN(`ID`))) AND (`Group_Members`.GroupID IN (1)) GROUP BY `Member`.ID ORDER BY Surname, FirstName LIMIT 0, 10)
line 157 of SQLQuery.php

SQLQuery->execute()
line 1519 of DataObject.php

DataObject->instance_get(Array,, INNER JOIN `Group_Members` ON `Group_Members`.MemberID = `Member`.ID,0, 10,ComponentSet)
line 90 of Group.php

Group->Members(10,0,Array,)
line 339 of MemberTableField.php

MemberTableField->sourceItems()
line 174 of ComplexTableField.php

ComplexTableField->FieldHolder()
line of

call_user_func_array(Array,Array)
line 404 of ViewableData.php

ViewableData->XML_val(FieldHolder,,1)
line 72 of .cache......sapphire.templates.TabSetFieldHolder.ss

include(/tmp/silverstripe-cache-...../.cache.......sapphire.templates.TabSetFieldHolder.ss)
line 197 of SSViewer.php

SSViewer->process(TabSet)
line 763 of ViewableData.php

ViewableData->renderWith(TabSetFieldHolder)
line 42 of TabSet.php

TabSet->FieldHolder()
line of

call_user_func_array(Array,Array)
line 404 of ViewableData.php

ViewableData->XML_val(FieldHolder,,1)
line 62 of .cache.....sapphire.templates.Includes.Form.ss

include(....sapphire.templates.Includes.Form.ss)
line 197 of SSViewer.php

SSViewer->process(Form)
line 763 of ViewableData.php

ViewableData->renderWith(Form)
line 644 of Form.php
Form->forTemplate()
line 655 of Form.php
Form->formHtmlContent()
line 228 of LeftAndMain.php
LeftAndMain->getitem(Array)
line 261 of Controller.php
Controller->run(Array)
line 104 of Director.php
Director::direct(admin/security/getitem)
line 174 of main.php

anyone an idea? deling with the wrong mysql version?
mysql version Client API version    5.0.32
php version PHP Version 5.2.6

No i havn't installed the forum module. Just the simple silverstripe installation with the i18n Module. The profile buttons works fine. can't deal with the i18n module because i tested the error before i installed the module an it was almost there.

i got a quite similar error (database error) with different tables, as i installed the i18n module an didn't do the db/build.

A question to the profis. the error says:

You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT `ID` FROM `Group_Members` WHERE `GroupID`='1' GROUP BY `,256)

It deals with the IN statement. right? hm...

The module is for translation. i hae english and german on my website. you can switch
and after hours and hours i figured out how you have to handle this module. phu