There are several reasons this could be happening.
1. Check how much RAM you have installed on your system. Gigastudio will run on 512mb of RAM, but you’ll be limited to just a few and simple instruments, complex orchestral samples like the Vienna libraries will likely only load an instrument or two.It’s recommended to have at least 1gig and up to 2gigs of RAM.
2. Make sure there are no other unnecessary programs loaded and that your machine is tweaked for audio. For more help with this, check our Windows XP Optimization Guide in the Tech Support Knowledge Base at our website.
3. Your system’s polyphony setting may be set too high and the polyphony may be taking up RAM which you could be using to load instruments. You can change this by going to File – System settings – Synthesizer, and change the polyphony slider. The amount of system memory used for streaming samples (polyphony) and loading instruments will be displayed on the green & blue meter.
4. Make sure you’re not loading groups of instruments- in the file loading box, if the instrument has a + sign next to it, that means there are multiple instruments within it, you can click the + and load an individual instrument from the drop-down list instead of loading them all. This can save a great deal of memory usage.
5. Take note of the samples you’re loading. It may be that you’re simply loading huge samples that take a large chunk of memory. Typically, the simpler the samples sound, the simpler they are.