Hi,
I just got the problem, some numbers in text formatted 
cells are recognited as type date ( int(0x16) ) with 
negative value.
In the follow function createDate in reader.php fails 
because of negative date values are not supported by 
PHP.
As a really bad workaround (I not really know what I do :
-/ ), I modified the following code (added 4 lines) in 
function _parsesheet($spos):
case Spreadsheet_Excel_Reader_Type_RK:
case Spreadsheet_Excel_Reader_Type_RK2:
$row = ord($this->data[$spos]) | 
ord($this->data[$spos+1])<<8;
$column = ord($this->data[$spos+2]) | 
ord($this->data[$spos+3])<<8;
$rknum = $this->_GetInt4d($this->data, $spos + 6);
$numValue = $this->_GetIEEE754($rknum);
if ($this->isDate($spos)) {
list($string, $raw) = $this->createDate($numValue)
;
    // Meikelator workaround bugfix ... (he did'nt 
know, what he did .. but it fixes
    // false date type recognition ...
    if ($raw < 0) { // if date value not supported ...
        $string = $numValue; 
        unset($this->rectype);
    }
    // end meikelator bugfix ...
}else{
$raw = $numValue;
$string = sprintf($this->curformat, $numValue * 
$this->multiplier);
//$this->addcell(RKRecord($r));
}
$this->addcell($row, $column, $string, $raw);
//echo "Type_RK $row $column $string $raw 
{$this->curformat}\n";
break;
---------------------
it's crappy, but works ... any better idea?
thx4all : deka
(if you need more information about: let me know ...)