There are some problems during installation on MySQL (in release 2-2-5-8). For example in the application renewal scheme (file 2.2.4.6):

MySql.Data.MySqlClient.MySqlException: Can't create table 'mojoportal.mp_letter' (errno: 150) at MySql.Data.MySqlClient.MySqlStream.OpenPacket () at MySql.Data.MySqlClient.NativeDriver.ReadResult (UInt64 & affectedRows, Int64 & lastInsertId) at

And in particular in the performance lines:
ALTER TABLE mp_Letter
ADD CONSTRAINT `FK_Letter_letterinfo`
FOREIGN KEY ( `LetterInfoGuid`)
REFERENCES mp_LetterInfo ( `LetterInfoGuid`);

Error MYSQL:
Can't create table 'mojoportal. # Sql-d60_2d' (errno: 121)

---------------------

MySQL for windows (5.1)

windows xp sp 2 + patches

Yes there are problems with MYSQL 5.1,
I have with manual application of patches creates an interesting error in the database:

I unloaded dump base and found the following:

DROP TABLE IF EXISTS `mp_letterinfo`;
CREATE TABLE `mp_letterinfo` (
`LetterInfoGuid` varchar (36) NOT NULL,
`SiteGuid` varchar (36) NOT NULL,
`Title` varchar (255) NOT NULL,
`Description` text NOT NULL,
`AvailableToRoles` text NOT NULL,
`Enabled` tinyint (1) unsigned NOT NULL,
`AllowUserFeedback` tinyint (1) unsigned NOT NULL,
`AllowAnonFeedback` tinyint (1) unsigned NOT NULL,
`FromAddress` varchar (255) NOT NULL,
`FromName` varchar (255) NOT NULL,
`ReplyToAddress` varchar (255) NOT NULL,
`SendMode` int (11) NOT NULL,
`EnableViewAsWebPage` tinyint (1) unsigned NOT NULL,
`EnableSendLog` tinyint (1) unsigned NOT NULL,
`RolesThatCanEdit` text NOT NULL,
`RolesThatCanApprove` text NOT NULL,
`RolesThatCanSend` text NOT NULL,
`SubscriberCount` int (11) NOT NULL,
`CreatedUTC` datetime NOT NULL,
`CreatedBy` varchar (36) NOT NULL,
`LastModUTC` datetime NOT NULL,
`LastModBy` varchar (36) NOT NULL,
PRIMARY KEY ( `LetterInfoGuid`),
CONSTRAINT `FK_Letter_letterinfo` FOREIGN KEY ( `LetterInfoGuid`) REFERENCES `mp_letterinfo` ( `LetterInfoGuid`)
) ENGINE = InnoDB DEFAULT CHARSET = utf8;

Out of this code for the SQL unable to create a second limit.

ALTER TABLE mp_Letter
ADD CONSTRAINT `FK_Letter_letterinfo`
FOREIGN KEY ( `LetterInfoGuid`)
REFERENCES mp_LetterInfo ( `LetterInfoGuid`);

Error MYSQL:
Can't create table 'mojoportal. # Sql-d60_2d' (errno: 121)

I think you can send an error report in MYSQL, if accurately find a place mistakes MYSQL (when and under what conditions occurs), but I have no wish to send yet, there is only a desire to make work MOJO

Joe, maybe it is worth specify the documentation for instructions on what version of the database made tests? (simply there is only one mention of the release "MySQL 4.0.20 or newer installed. It may work with older versions but I have not tested it.")