Drupal encoding and node insert

I have a CCK type for storing mentions (Social Media search mentions). Some of the mentions I believe are ASCII (My knowledge of this stuff is little).

I retrieve data from API's, which I then using node_save to save to Drupal.

My question is, what should I use to safely convert whatever I am getting into a format Drupal and MySQL are happy with?

The particular db_query error I get is unhelpfull "Warning in test1\includes\common.inc on line 3538". Nice. I have traced it to be encoding, as I used the following code to make the input safe, but it is not working with all input.

$node->title = htmlentities($item['title'], ENT_COMPAT, 'UTF-8');

It worked well for some ASCII characters, like those square ones [] etc, but not for this "行けなくてもずっとユーミンは聴きつづけます".

I'm really stuck. :(

UPDATE: The EXACT error I get from PHP is "Warning in D:\sites\test1\includes\common.inc on line 3538", and the line reads "if (db_query($query, $values)) {".

UPDATE 2: I've confirmed that the encoding of the data I am receiving is UTF8. This really doesn't make sense now, and I've confirmed that the collation in the db is utf8_general_ci.

UPDATE 3: One of the title's is: How Much Does A Facebook Fan Cost?� $1.07

The output of:

var_export(array_map('ord', str_split($node->title))

gave me the character 160 for the funny question mark (which is a square like [] in eclipse).

UPDATE 4: MySQL version is 5.1.41, and the collation on the columns is utf8_general_ci.

UPDATE 5: I managed to get Drupal to print the query with db_queryd. Funny thing is now I get the exact error message and not "Warning in", but Drupal still doesn't have this error in the log! WTF. So the exact sql is:

INSERT INTO node (vid, type, language, title, uid, status, created, changed, comment, promote, moderate, sticky, tnid, translate) VALUES (0, 'sm_mention', '', 'How Much Does A Facebook Fan Cost?� $1.07 (Geoffrey A. Fowler/Digits)', 1, 1, 1298395302, 1298395302, 0, 0, 0, 0, 0, 0)

And the error given is: Incorrect string value: '\xA0 $1.0...' for column 'title' at row 1

This honestly sounds like something doesn't like extended ascii characters.

UPDATE 6:

 SHOW CREATE TABLE node: 

   CREATE TABLE `node` (
  `nid` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `vid` int(10) unsigned NOT NULL DEFAULT '0',
  `type` varchar(32) NOT NULL DEFAULT '',
  `language` varchar(12) NOT NULL DEFAULT '',
  `title` varchar(255) NOT NULL DEFAULT '',
  `uid` int(11) NOT NULL DEFAULT '0',
  `status` int(11) NOT NULL DEFAULT '1',
  `created` int(11) NOT NULL DEFAULT '0',
  `changed` int(11) NOT NULL DEFAULT '0',
  `comment` int(11) NOT NULL DEFAULT '0',
  `promote` int(11) NOT NULL DEFAULT '0',
  `moderate` int(11) NOT NULL DEFAULT '0',
  `sticky` int(11) NOT NULL DEFAULT '0',
  `tnid` int(10) unsigned NOT NULL DEFAULT '0',
  `translate` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY (`nid`),
  UNIQUE KEY `vid` (`vid`),
  KEY `node_changed` (`changed`),
  KEY `node_created` (`created`),
  KEY `node_moderate` (`moderate`),
  KEY `node_promote_status` (`promote`,`status`),
  KEY `node_status_type` (`status`,`type`,`nid`),
  KEY `node_title_type` (`title`,`type`(4)),
  KEY `node_type` (`type`(4)),
  KEY `uid` (`uid`),
  KEY `tnid` (`tnid`),
  KEY `translate` (`translate`)
) ENGINE=InnoDB AUTO_INCREMENT=1700 DEFAULT CHARSET=utf8

\xA0 is not a valid start of a UTF8 sequence.

The character known as NO-BREAK SPACE having the Unicode codepoint 0x00A0 should be encoded as 0xC2A0 in UTF8.

Thus said, your input string is broken, it's not a valid UTF8.