windows 7 recovery problem

I have a hp slim pc It was upgraded using hps own upgrade dvd and install assistant , the pc works fine but with the exception of one thing the recovery cd creation , an error of incorrect parameters and the usual stop symbol pops up ending in error ***57 which ive found on the net, researched and tried replacing recd.exe that made no dif either, I have made a successful backup to an external freecom drive which seems to work fine , i only found out that the cd recovery didnt work as i used it to check as you should that the complete pc recovery actually worked, fortunately i did have a spare cd from my other desktop , so i can use that should problems arise,( the only difference between my two desktops is one is oem and the other has a full retail windows 7 which i upgraded over vista premium as hp wouldnt sell me oem upgrade dvd set for my model as it didnt come within microsofts cut off date for free upgrades.) Its bugging me that i cant find any simple solution , ms want cash to give support as its oem , hp support are as useful as a chocolate fireguard so ive decided to ask here, it isnt anything to do with dodgy cd or dvd media , as ive tried that too! vista apparently had similar issues so no doubt this is similar to windows 7 any ideas please