If you have just purchased a VPS the reason it may not boot right away is due to changes in the device mapping in the latest kernels, sadly solusvm have no system to account for these changes so some manual work is required this side to get things as they should be, it is simply changing the device type in your xen config file.
Please open a ticket for this is will be dealt with asap in the mean time a suggestion has been put forward to solusvm for long term resolution.
