[TYPO3-dam] DAM 1.0.101 - bug or misuse?

[Dr. Ronald P. Steiner]

Hi List,

I get this lines at the top of each page of the back end modules of DAM:

Warning: imagecreatefrompng() [function.imagecreatefrompng]: 
'C:/xampp/htdocs/t3420/typo3temp/readPG_cebb0c714301be0a0b157629f548829a.png' 
is not a valid PNG file in 
C:\xampp\htdocs\t3420\t3lib\class.t3lib_iconworks.php on line 503

Warning: imagecolorstotal(): supplied argument is not a valid Image 
resource in C:\xampp\htdocs\t3420\t3lib\class.t3lib_iconworks.php on 
line 386

Warning: imagedestroy(): supplied argument is not a valid Image resource 
in C:\xampp\htdocs\t3420\t3lib\class.t3lib_iconworks.php on line 452

am I doing something wrong? or is this a bug?

greetings

Ron