You'll need to get a 1.48 ROM and flash back to that using the sd card method to get back to SPL 1.42. Then you can put HSPL on the phone and upgrade again using the activesync method and you'll be ok.
You can get the 1.48 ROM here, just put in your serial number:
Then follow these notes:
Flashing Via MicroSD Card
NOTE (PLEASE READ): If you flash a Stock Rom via microSD Card then it will overwrite your HardSPL with a stock SPL included in the nbh file. Therefore if you flash a v2.01 or later Rom (with SPL2.*) you will NOT be able to reinstall HardSPL onto your device and could end up bricking it. This does not apply to custom roms as they do not include an SPL. BE CAREFUL!!
1. Make sure your microSD is Formatted to fat32 (you dont have to delete all files but it is safer if you do)
2. Download your prefered Rom from the LEO Rom Develpoment Page and unzip/unrar it to your PC
3. Goto the Roms Folder and rename the .nbh file to LEOIMG.nbh
4. Copy the LEOIMG.nbh file to the root of your MicroSD Card
5. Plug the MicroSD Card into the phone
6. Reset the device while pressing the volume down button to enter the BootLoader screen, you will first see a tri-color screen with the phone and SPL Information at the top
7. Follow the On Screen instructions to start the update
8. After flash has completed, press the reset button with the stylus to reset the device.